497

	SIDLEY AUSTIN LLP 787 SEVENTH AVENUE NEW YORK, NY 10019 (212) 839 5300 (212) 839 5599 FAX	BEIJING BRUSSELS CHICAGO DALLAS FRANKFURT GENEVA HONG KONG HOUSTON LONDON	LOS ANGELES NEW YORK PALO ALTO SAN FRANCISCO SHANGHAI SINGAPORE SYDNEY TOKYO WASHINGTON, D.C.
		FOUNDED 1866

February 22, 2013

VIA EDGAR

Securities and Exchange Commission

100 F Street, NE

Washington, DC 20549

Re: BlackRock Global Opportunities Portfolio, BlackRock International Opportunities Portfolio, BlackRock Health Sciences Opportunities Portfolio and BlackRock Science & Technology Opportunities Portfolio, each a series of BlackRock Funds^SM

(File Nos. 33-26305, 811-05742)

Ladies and Gentlemen:

On behalf of BlackRock Funds^SM, attached for filing are exhibits containing interactive data format risk/return summary information that mirrors the risk/return summary information in the Prospectuses of BlackRock Global Opportunities Portfolio, BlackRock International Opportunities Portfolio, BlackRock Health Sciences Opportunities Portfolio and BlackRock Science & Technology Opportunities Portfolio (the “Funds”), dated January 28, 2013, as filed pursuant to Rule 497(e) under the Securities Act of 1933, on February 4, 2013 (the “497 Filing”). The purpose of this filing is to submit the 497 Filing in XBRL for the Funds.

Any questions or comments on the 497 Filing should be directed to the undersigned at (212) 839-5583.

Very truly yours,

/s/ Ellen W. Harris                            

Ellen W. Harris

Enclosures

cc: Benjamin Archibald, Esq.

BlackRock Advisors, LLC

Sidley Austin (NY) LLP is a Delaware limited liability partnership doing business as Sidley Austin LLP and practicing in affiliation with other Sidley Austin partnerships.

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Service Shares | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock International Opportunities Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock International Opportunities Portfolio (“International Opportunities” or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to seek long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Services Shares of International Opportunities.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	February 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 99% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	99.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund’s most recent annual report which does not include the Acquired Fund Fees and Expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, International Opportunities invests at least 80% of its net assets in equity securities issued by foreign companies of any market capitalization. The Fund may invest up to 40% of its net assets in stocks of issuers in emerging market countries. The Fund seeks to buy primarily common stock but can also invest in preferred stock and convertible securities. From time to time the Fund may invest in shares of companies through initial public offerings (“IPOs”). The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies, or enter into foreign currency transactions, including swaps (collectively, commonly known as derivatives). The Fund typically uses derivatives as a substitute for taking a position in the underlying asset and/or as part of a strategy designed to reduce exposure to other risks, such as currency risk. The Fund may also use derivatives to enhance returns, in which case their use would involve leveraging risk. The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may also use forward foreign currency exchange contracts (obligations to buy or sell a currency at a set rate in the future).
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in International Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock. Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives. Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include: — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight. — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio. — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries. — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws. — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments. — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies. “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering. Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The information shows you how International Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the MSCI All Country World Index Ex-U.S. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how International Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Service Shares ANNUAL TOTAL RETURNS BlackRock International Opportunities Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the ten-year period shown in the bar chart, the highest return for a quarter was 28.04% (quarter ended June 30, 2009) and the lowest return for a quarter was –24.50% (quarter ended September 30, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Service Shares | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | Service Shares
Risk/Return:	rr_RiskReturnAbstract
Management Fee	rr_ManagementFeesOverAssets	0.98%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.67%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.91%	[1]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.10%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.81%	[2]
1 Year	rr_ExpenseExampleYear01	184
3 Years	rr_ExpenseExampleYear03	590
5 Years	rr_ExpenseExampleYear05	1,022
10 Years	rr_ExpenseExampleYear10	2,225
2003	rr_AnnualReturn2003	48.82%
2004	rr_AnnualReturn2004	23.70%
2005	rr_AnnualReturn2005	31.83%
2006	rr_AnnualReturn2006	31.55%
2007	rr_AnnualReturn2007	18.12%
2008	rr_AnnualReturn2008	(43.33%)
2009	rr_AnnualReturn2009	36.52%
2010	rr_AnnualReturn2010	11.25%
2011	rr_AnnualReturn2011	(14.53%)
2012	rr_AnnualReturn2012	17.77%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	28.04%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(24.50%)
1 Year	rr_AverageAnnualReturnYear01	17.77%
5 Years	rr_AverageAnnualReturnYear05	(2.83%)
10 Years	rr_AverageAnnualReturnYear10	12.57%
Service Shares | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions | Service Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	17.56%
5 Years	rr_AverageAnnualReturnYear05	(2.91%)
10 Years	rr_AverageAnnualReturnYear10	11.75%
Service Shares | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions and Sale of Shares | Service Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	11.82%
5 Years	rr_AverageAnnualReturnYear05	(2.35%)
10 Years	rr_AverageAnnualReturnYear10	11.19%
Service Shares | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | MSCI All Country World Index Ex-U.S (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	16.83%
5 Years	rr_AverageAnnualReturnYear05	(2.89%)
10 Years	rr_AverageAnnualReturnYear10	9.74%

[1] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

[2] As described in the "Management of the Funds" section of the Fund's prospectus on pages 40-46, BlackRock Advisors, LLC ("BlackRock") has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 1.80% of average daily net assets until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

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Service Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO

Fund Overview

Key Facts About BlackRock Science & Technology Opportunities Portfolio

Investment Objective

The investment objective of BlackRock Science & Technology Opportunities Portfolio (“Science & Technology Opportunities” or the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is to provide long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold Services Shares of Science & Technology Opportunities.

Annual Fund Operating Expenses
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Service Shares BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO
Management Fee		0.90%
Distribution and/or Service (12b-1) Fees		0.25%
Other Expenses		0.42%
Acquired Fund Fees and Expenses	[1]	0.01%
Total Annual Fund Operating Expenses	[1]	1.58%
Fee Waivers and/or Expense Reimbursements	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[2]	1.58%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Service Shares BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO	161	499	860	1,878

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 320% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Under normal market conditions, Science & Technology Opportunities invests at least 80% of its net assets in equity securities issued by U.S. and non-U.S. science and technology companies in all market capitalization ranges, selected for their rapid and sustainable growth potential from the development, advancement and use of science and/or use of technology. The Fund may invest up to 25% of its net assets in emerging market countries.

Some of the industries likely to be represented in the Fund’s portfolio holdings include: application software, IT consulting and services, internet software and services, networking equipment, telecom equipment, computer hardware, computer storage and peripherals, electronic equipment and instruments, semiconductors and equipment, aerospace and defense, electrical components and equipment, biotechnology, pharmaceuticals, healthcare equipment and supplies, healthcare distribution and services, healthcare facilities, industrial gases, specialty chemicals, advanced materials, internet and catalog retail, integrated telecom services, alternative carriers and wireless telecommunication services.

The Fund seeks to invest primarily in common stock but may also invest in preferred stock and convertible securities. The Fund may also invest in Rule 144A securities, which are privately placed securities purchased by qualified institutional buyers. From time to time the Fund may invest in shares of companies through initial public offerings (“IPOs”).

The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies, or enter into foreign currency transactions, including swaps (collectively, commonly known as derivatives). The Fund typically uses derivatives as a substitute for taking a position in the underlying asset and/or as part of a strategy designed to reduce exposure to other risks, such as currency risk. The Fund may also use derivatives to enhance returns, in which case their use would involve leveraging risk. The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may also use forward foreign currency exchange contracts (obligations to buy or sell a currency at a set rate in the future).

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in Science & Technology Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Concentration Risk — The Fund’s strategy of concentrating in science and technology and related companies means that its performance will be closely tied to the performance of a particular market segment. The Fund’s concentration in these companies may present more risks than if it were broadly diversified over numerous industries and sectors of the economy. A downturn in these companies would have a larger impact on the Fund than on a mutual fund that does not concentrate in such companies. At times, the performance of these companies will lag the performance of other industries or the broader market as a whole.

• Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock.

• Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives.

• Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include:
  
  — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight.
  
  — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.
  
  — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position.
  
  — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries.
  
  — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws.
  
  — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments.
  
  — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments.

• Geographic Concentration Risk — From time to time the Fund may invest a substantial amount of its assets in issuers located in a single country or a limited number of countries. If the Fund concentrates its investments in this manner, it assumes the risk that economic, political and social conditions in those countries will have a significant impact on its investment performance. The Fund’s investment performance may also be more volatile if it concentrates its investments in certain countries, especially emerging market countries.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies.

• “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.

• Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.

• Technology Securities Risk — Certain technology related companies may face special risks that their products or services may not prove to be commercially successful. Technology related companies are also strongly affected by worldwide scientific or technological developments. As a result, their products may rapidly become obsolete. Such companies are also often subject to governmental regulation and may, therefore, be adversely affected by governmental policies.

Performance Information

The information shows you how Science & Technology Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the NYSE Arca Tech 100 Index^SM. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Service Shares
ANNUAL TOTAL RETURNS
BlackRock Science & Technology Opportunities Portfolio
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 30.03% (quarter ended June 30, 2003) and the lowest return for a quarter was –22.21% (quarter ended December 31, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Service Shares	1 Year	5 Years		10 Years
BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO	7.38%	1.16%	[1]	9.40%	[1]
BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO Return After Taxes on Distributions	7.38%	1.16%	[1]	9.40%	[1]
BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO Return After Taxes on Distributions and Sale of Shares	4.80%	0.99%	[1]	8.39%	[1]
BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO NYSE Arca Tech 100 Index℠ (Reflects no deduction for fees, expenses or taxes)	21.46%	7.62%	[1]	11.69%	[1]

After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

[1] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

[2] As described in the "Management of the Funds" section of the Fund's prospectus on pages 40-46, BlackRock Advisors, LLC ("BlackRock") has contractually agreed to waive or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 1.78% of average daily net assets until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in a settlement of litigation.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in a settlement of litigation.

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Investor, Institutional and R Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock Science & Technology Opportunities Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock Science & Technology Opportunities Portfolio (“Science & Technology Opportunities” or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to provide long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of Science & Technology Opportunities. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 47 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that are deducted from Fund assets)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	February 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 320% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	320.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”).
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	25,000
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	You would pay the following expenses if you did not redeem your shares:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, Science & Technology Opportunities invests at least 80% of its net assets in equity securities issued by U.S. and non-U.S. science and technology companies in all market capitalization ranges, selected for their rapid and sustainable growth potential from the development, advancement and use of science and/or use of technology. The Fund may invest up to 25% of its net assets in emerging market countries. Some of the industries likely to be represented in the Fund’s portfolio holdings include: application software, IT consulting and services, internet software and services, networking equipment, telecom equipment, computer hardware, computer storage and peripherals, electronic equipment and instruments, semiconductors and equipment, aerospace and defense, electrical components and equipment, biotechnology, pharmaceuticals, healthcare equipment and supplies, healthcare distribution and services, healthcare facilities, industrial gases, specialty chemicals, advanced materials, internet and catalog retail, integrated telecom services, alternative carriers and wireless telecommunication services. The Fund seeks to invest primarily in common stock but may also invest in preferred stock and convertible securities. The Fund may also invest in Rule 144A securities, which are privately placed securities purchased by qualified institutional buyers. From time to time the Fund may invest in shares of companies through initial public offerings (“IPOs”). The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies, or enter into foreign currency transactions, including swaps (collectively, commonly known as derivatives). The Fund typically uses derivatives as a substitute for taking a position in the underlying asset and/or as part of a strategy designed to reduce exposure to other risks, such as currency risk. The Fund may also use derivatives to enhance returns, in which case their use would involve leveraging risk. The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may also use forward foreign currency exchange contracts (obligations to buy or sell a currency at a set rate in the future).
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in Science & Technology Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Concentration Risk — The Fund’s strategy of concentrating in science and technology and related companies means that its performance will be closely tied to the performance of a particular market segment. The Fund’s concentration in these companies may present more risks than if it were broadly diversified over numerous industries and sectors of the economy. A downturn in these companies would have a larger impact on the Fund than on a mutual fund that does not concentrate in such companies. At times, the performance of these companies will lag the performance of other industries or the broader market as a whole. Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock. Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives. Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include: — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight. — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio. — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries. — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws. — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments. — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments. Geographic Concentration Risk — From time to time the Fund may invest a substantial amount of its assets in issuers located in a single country or a limited number of countries. If the Fund concentrates its investments in this manner, it assumes the risk that economic, political and social conditions in those countries will have a significant impact on its investment performance. The Fund’s investment performance may also be more volatile if it concentrates its investments in certain countries, especially emerging market countries. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies. “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering. Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies. Technology Securities Risk — Certain technology related companies may face special risks that their products or services may not prove to be commercially successful. Technology related companies are also strongly affected by worldwide scientific or technological developments. As a result, their products may rapidly become obsolete. Such companies are also often subject to governmental regulation and may, therefore, be adversely affected by governmental policies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The information shows you how Science & Technology Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the NYSE Arca Tech 100 IndexSM. The returns for Class R Shares prior to October 2, 2006, the commencement of operations of Class R Shares, are based upon performance of the Fund’s Institutional Shares. The returns for Class R Shares, however, are adjusted to reflect the class-specific fees applicable to Class R Shares at the time of such share class’ launch. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how Science & Technology Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Investor A Shares ANNUAL TOTAL RETURNS BlackRock Science & Technology Opportunities Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the periods shown in the bar chart, the highest return for a quarter was 29.92% (quarter ended June 30, 2003) and the lowest return for a quarter was –22.29% (quarter ended December 31, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.
Investor, Institutional and R Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.25%
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none	[1]
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.57%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.73%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.73%	[3]
1 Year	rr_ExpenseExampleYear01	692
3 Years	rr_ExpenseExampleYear03	1,041
5 Years	rr_ExpenseExampleYear05	1,414
10 Years	rr_ExpenseExampleYear10	2,459
2003	rr_AnnualReturn2003	58.36%
2004	rr_AnnualReturn2004	2.18%
2005	rr_AnnualReturn2005	11.15%
2006	rr_AnnualReturn2006	7.67%
2007	rr_AnnualReturn2007	19.18%
2008	rr_AnnualReturn2008	(39.89%)
2009	rr_AnnualReturn2009	56.21%	[4]
2010	rr_AnnualReturn2010	17.99%
2011	rr_AnnualReturn2011	(11.31%)
2012	rr_AnnualReturn2012	7.25%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	29.92%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.29%)
1 Year	rr_AverageAnnualReturnYear01	1.66%
5 Years	rr_AverageAnnualReturnYear05	(0.02%)	[4]
10 Years	rr_AverageAnnualReturnYear10	8.70%	[4]
Investor, Institutional and R Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | Investor B Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	4.50%	[5]
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.62%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.53%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.53%	[3]
1 Year	rr_ExpenseExampleYear01	706
3 Years	rr_ExpenseExampleYear03	1,138
5 Years	rr_ExpenseExampleYear05	1,545
10 Years	rr_ExpenseExampleYear10	2,670
1 Year	rr_ExpenseExampleNoRedemptionYear01	256
3 Years	rr_ExpenseExampleNoRedemptionYear03	788
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,345
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,670
1 Year	rr_AverageAnnualReturnYear01	1.94%
5 Years	rr_AverageAnnualReturnYear05	(0.23%)	[4]
10 Years	rr_AverageAnnualReturnYear10	8.57%	[4]
Investor, Institutional and R Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | Investor C Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[6]
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.70%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.61%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.61%	[3]
1 Year	rr_ExpenseExampleYear01	364
3 Years	rr_ExpenseExampleYear03	811
5 Years	rr_ExpenseExampleYear05	1,385
10 Years	rr_ExpenseExampleYear10	2,944
1 Year	rr_ExpenseExampleNoRedemptionYear01	264
3 Years	rr_ExpenseExampleNoRedemptionYear03	811
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,385
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,944
1 Year	rr_AverageAnnualReturnYear01	5.31%
5 Years	rr_AverageAnnualReturnYear05	0.17%	[4]
10 Years	rr_AverageAnnualReturnYear10	8.36%	[4]
Investor, Institutional and R Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | Institutional Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.55%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.46%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.06%)	[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.40%	[3]
1 Year	rr_ExpenseExampleYear01	143
3 Years	rr_ExpenseExampleYear03	456
5 Years	rr_ExpenseExampleYear05	792
10 Years	rr_ExpenseExampleYear10	1,741
1 Year	rr_AverageAnnualReturnYear01	7.57%
5 Years	rr_AverageAnnualReturnYear05	1.43%	[4]
10 Years	rr_AverageAnnualReturnYear10	9.72%	[4]
Investor, Institutional and R Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | Class R Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.60%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.01%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.01%	[3]
1 Year	rr_ExpenseExampleYear01	204
3 Years	rr_ExpenseExampleYear03	630
5 Years	rr_ExpenseExampleYear05	1,083
10 Years	rr_ExpenseExampleYear10	2,338
1 Year	rr_AverageAnnualReturnYear01	6.96%
5 Years	rr_AverageAnnualReturnYear05	0.72%	[4]
10 Years	rr_AverageAnnualReturnYear10	8.92%	[4]
Investor, Institutional and R Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.66%
5 Years	rr_AverageAnnualReturnYear05	(0.02%)	[4]
10 Years	rr_AverageAnnualReturnYear10	8.70%	[4]
Investor, Institutional and R Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions and Sale of Shares | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	1.08%
5 Years	rr_AverageAnnualReturnYear05	(0.02%)	[4]
10 Years	rr_AverageAnnualReturnYear10	7.74%	[4]
Investor, Institutional and R Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | NYSE Arca Tech 100 Index℠ (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	21.46%
5 Years	rr_AverageAnnualReturnYear05	7.62%	[4]
10 Years	rr_AverageAnnualReturnYear10	11.69%	[4]

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

[3] As described in the "Management of the Funds" section of the Fund's prospectus on pages 62-70, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.80% (for Investor A Shares), 2.73% (for Investor B and Investor C Shares), 1.39% (for Institutional Shares) and 2.57% (for Class R Shares) until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[4] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in a settlement of litigation.

[5] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[6] There is no CDSC on Investor C Shares after one year.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock Health Sciences Opportunities Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock Health Sciences Opportunities Portfolio (“Health Sciences Opportunities” or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to provide long-term growth of capital.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of Health Sciences Opportunities. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 47 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	February 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 135% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	135.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	A contingent deferred sales charge (“CDSC”) of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”).
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	25,000
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund’s most recent annual report which does not include the Acquired Fund Fees and Expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	You would pay the following expenses if you did not redeem your shares:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, Health Sciences Opportunities invests at least 80% of total assets in equity securities, primarily common stock, of companies in health sciences and related industries. The health sciences sector can include companies in health care equipment and supplies, health care providers and services, biotechnology, and pharmaceuticals. Health sciences and related industries can include, but are not limited to, businesses involved in the development, production, and distribution or delivery of medical and pharmaceutical products and services, companies engaged in biotechnology and medical research and development, companies that may design, manufacture or distribute medical, dental and optical equipment and supplies, including diagnostic equipment, and companies that may also provide diagnostic services or operate health facilities and hospitals, or provide related administrative, management and financial support. The Fund will concentrate its investments (i.e., invest more than 25% of its assets) in health sciences or related industries, and may invest in companies located in non-U.S. countries. The Fund reserves the right to invest up to 20% of total assets in other types of securities. These may include stocks of companies not associated with health sciences. The Fund is classified as non-diversified under the Investment Company Act of 1940, as amended, which means that it can invest more of its assets in fewer companies than a diversified fund.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	The Fund will concentrate its investments (i.e., invest more than 25% of its assets) in health sciences or related industries, and may invest in companies located in non-U.S. countries.
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in Health Sciences Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Concentration Risk — The Fund’s strategy of concentrating in health sciences and related companies means that its performance will be closely tied to the performance of a particular market segment. The Fund’s concentration in these companies may present more risks than if it were broadly diversified over numerous industries and sectors of the economy. A downturn in these companies would have a larger impact on the Fund than on a mutual fund that does not concentrate in such companies. At times, the performance of these companies will lag the performance of other industries or the broader market as a whole. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include: —  The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight. — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio. — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries. — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws. — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments. — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments. Healthcare-Related Securities Risk — Many healthcare-related companies are smaller and less seasoned than companies in other sectors. Healthcare-related companies may also be strongly affected by scientific or technological developments and their products may quickly become obsolete. Many healthcare companies are heavily dependent on patent protection and the actual or perceived safety and efficiency of their products. The expiration of patents may adversely affect the profitability of these companies. Many healthcare companies are subject to extensive litigation based on product liability and similar claims. Finally, many healthcare-related companies offer products and services that are subject to governmental regulation and may be adversely affected by changes in governmental policies or laws. In March 2010, President Obama signed into law the Patient Protection and Affordable Care Act designed to reform the healthcare industry. The Fund cannot predict the impact of this legislation on healthcare-related companies or what healthcare-related proposals might be proposed or enacted in the future. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies. Non-Diversification Risk — The Fund is a non-diversified fund. Because the Fund may invest in securities of a smaller number of issuers, it may be more exposed to the risks associated with and developments affecting an individual issuer than a fund that invests more widely. Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Non-Diversification Risk — The Fund is a non-diversified fund. Because the Fund may invest in securities of a smaller number of issuers, it may be more exposed to the risks associated with and developments affecting an individual issuer than a fund that invests more widely.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	On January 31, 2005, Health Sciences Opportunities reorganized with the State Street Research Health Sciences Fund (the “SSR Fund”). For periods prior to January 31, 2005, the chart and table show performance information for the SSR Fund, which had investment objectives and strategies substantially similar to the Fund. The performance of Investor B and Investor C Shares for the period before they were launched is based on the performance of Investor A Shares, adjusted to reflect the class specific fees applicable to Investor B and Investor C Shares, respectively, at the time of such share class’ launch. Class R Shares commenced operations on September 12, 2011, therefore the returns in the table for Class R Shares prior to commencement date are based on the Fund’s Institutional Shares, adjusted to reflect the fees and expenses applicable to Class R Shares. This information may be considered when assessing the Fund’s performance, but does not represent the actual performance of these share classes. The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Standard & Poor’s (“S&P”) 500® Index. The table also compares the Fund’s performance to that of the Russell 3000® Health Care Index, which is relevant to the Fund because it has characteristics similar to the Fund’s investment strategies. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Investor A Shares ANNUAL TOTAL RETURNS BlackRock Health Sciences Opportunities Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the ten-year period shown in the bar chart, the highest return for a quarter was 34.69% (quarter ended June 30, 2003) and the lowest return for a quarter was –13.97% (quarter ended December 31, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.
Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.25%
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none	[1]
Management Fees	rr_ManagementFeesOverAssets	0.73%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.30%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.30%	[3]
1 Year	rr_ExpenseExampleYear01	650
3 Years	rr_ExpenseExampleYear03	915
5 Years	rr_ExpenseExampleYear05	1,200
10 Years	rr_ExpenseExampleYear10	2,010
2003	rr_AnnualReturn2003	66.64%
2004	rr_AnnualReturn2004	14.56%
2005	rr_AnnualReturn2005	16.83%
2006	rr_AnnualReturn2006	8.24%
2007	rr_AnnualReturn2007	20.35%
2008	rr_AnnualReturn2008	(19.33%)
2009	rr_AnnualReturn2009	27.25%
2010	rr_AnnualReturn2010	7.16%
2011	rr_AnnualReturn2011	5.97%
2012	rr_AnnualReturn2012	18.39%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	34.69%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(13.97%)
1 Year	rr_AverageAnnualReturnYear01	12.17%
5 Years	rr_AverageAnnualReturnYear05	5.51%
10 Years	rr_AverageAnnualReturnYear10	14.28%
Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Investor B Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	4.50%	[4]
Management Fees	rr_ManagementFeesOverAssets	0.73%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.34%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.08%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.08%	[3]
1 Year	rr_ExpenseExampleYear01	661
3 Years	rr_ExpenseExampleYear03	1,002
5 Years	rr_ExpenseExampleYear05	1,319
10 Years	rr_ExpenseExampleYear10	2,211
1 Year	rr_ExpenseExampleNoRedemptionYear01	211
3 Years	rr_ExpenseExampleNoRedemptionYear03	652
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,119
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,211
1 Year	rr_AverageAnnualReturnYear01	12.99%
5 Years	rr_AverageAnnualReturnYear05	5.50%
10 Years	rr_AverageAnnualReturnYear10	14.19%
Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Investor C Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[5]
Management Fees	rr_ManagementFeesOverAssets	0.73%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.28%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.02%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.02%	[3]
1 Year	rr_ExpenseExampleYear01	305
3 Years	rr_ExpenseExampleYear03	634
5 Years	rr_ExpenseExampleYear05	1,088
10 Years	rr_ExpenseExampleYear10	2,348
1 Year	rr_ExpenseExampleNoRedemptionYear01	205
3 Years	rr_ExpenseExampleNoRedemptionYear03	634
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,088
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,348
1 Year	rr_AverageAnnualReturnYear01	16.58%
5 Years	rr_AverageAnnualReturnYear05	5.89%
10 Years	rr_AverageAnnualReturnYear10	14.08%
Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Institutional Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fees	rr_ManagementFeesOverAssets	0.73%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.25%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.99%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	0.99%	[3]
1 Year	rr_ExpenseExampleYear01	101
3 Years	rr_ExpenseExampleYear03	315
5 Years	rr_ExpenseExampleYear05	547
10 Years	rr_ExpenseExampleYear10	1,213
1 Year	rr_AverageAnnualReturnYear01	18.77%
5 Years	rr_AverageAnnualReturnYear05	6.99%
10 Years	rr_AverageAnnualReturnYear10	15.25%
Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Class R Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fees	rr_ManagementFeesOverAssets	0.73%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.47%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.71%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.71%	[3]
1 Year	rr_ExpenseExampleYear01	174
3 Years	rr_ExpenseExampleYear03	539
5 Years	rr_ExpenseExampleYear05	928
10 Years	rr_ExpenseExampleYear10	2,019
1 Year	rr_AverageAnnualReturnYear01	17.92%
5 Years	rr_AverageAnnualReturnYear05	6.17%
10 Years	rr_AverageAnnualReturnYear10	14.35%
Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Return After Taxes On Distributions | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	10.80%
5 Years	rr_AverageAnnualReturnYear05	4.51%
10 Years	rr_AverageAnnualReturnYear10	13.32%
Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Return After Taxes On Distributions And Sale Of Shares | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	9.25%
5 Years	rr_AverageAnnualReturnYear05	4.42%
10 Years	rr_AverageAnnualReturnYear10	12.48%
Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Russell 3000® Health Care Index (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	19.32%
5 Years	rr_AverageAnnualReturnYear05	5.52%
10 Years	rr_AverageAnnualReturnYear10	7.13%
Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | S&P 500® Index (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	16.00%
5 Years	rr_AverageAnnualReturnYear05	1.66%
10 Years	rr_AverageAnnualReturnYear10	7.10%

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

[3] As described in the "Management of the Funds" section of the Fund's prospectus on pages 62-70, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.81% for Class R Shares until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[4] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[5] There is no CDSC on Investor C Shares after one year.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Document Creation Date	dei_DocumentCreationDate	Feb. 04, 2013

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Investor, Institutional and R Shares | BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock Global Opportunities Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock Global Opportunities Portfolio (“Global Opportunities” or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to provide long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of Global Opportunities. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 47 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	February 1, 2015
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 122% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	122.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”).
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	25,000
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	You would pay the following expenses if you did not redeem your shares:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal conditions, Global Opportunities will invest at least 75% of its total assets in global equity securities of any market capitalization, selected for their above-average return potential. The Fund seeks to buy primarily common stock but may also invest in preferred stock and convertible securities. The Fund may invest up to 25% of its total assets in stocks of issuers in emerging market countries. The Fund may invest up to 25% of its total assets in global fixed income securities, including corporate bonds, U.S. government debt securities, non-U.S. government and supranational debt securities, asset-backed securities, mortgage-backed securities, emerging market debt securities and non-investment grade debt securities (high yield or junk bonds). Investment in fixed income securities will be made on an opportunistic basis. Securities will be identified based on factors such as relative value and earnings estimate revisions. From time to time, the Fund may invest in shares of companies through initial public offerings (“IPOs”). The Fund will invest in securities of non-U.S. issuers that can be U.S. dollar based or non-U.S. dollar based on a hedged or unhedged basis. The Fund may enter into currency transactions on a hedged or unhedged basis in order to seek total return. The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies, or enter into foreign currency transactions, including swaps (collectively, commonly known as derivatives). The Fund typically uses derivatives as a substitute for taking a position in the underlying asset and/or as part of a strategy designed to reduce exposure to other risks, such as currency risk. The Fund may also use derivatives to enhance returns, in which case their use would involve leveraging risk. The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may also use forward foreign currency exchange contracts (obligations to buy or sell a currency at a set rate in the future).
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in Global Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock. Debt Securities Risk — Debt securities, such as bonds, involve credit risk. Credit risk is the risk that the borrower will not make timely payments of principal and interest. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. The degree of credit risk depends on the issuer’s financial condition and on the terms of the securities. Debt securities are also subject to interest rate risk. Interest rate risk is the risk that the value of a debt security may fall when interest rates rise. In general, the market price of debt securities with longer maturities will go up or down more in response to changes in interest rates than the market price of shorter term securities. Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives. Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include: — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight. — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio. — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries. — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws. — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments. — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies. “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering. Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The information shows you how Global Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the average annual total returns of each class of the Fund’s shares with that of the MSCI All Country World Index. Class R Shares commenced operations on September 12, 2011, therefore the returns in the table for Class R Shares prior to commencement date are based on the Fund’s Institutional Shares, adjusted to reflect the fees and expenses applicable to Class R Shares. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how Global Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Investor A Shares ANNUAL TOTAL RETURNS BlackRock Global Opportunities Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the periods shown in the bar chart, the highest return for a quarter was 24.03% (quarter ended June 30, 2009) and the lowest return for a quarter was –21.57% (quarter ended December 31, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.
Investor, Institutional and R Shares | BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.25%
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none	[1]
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.37%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.52%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.19%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.33%	[2]
1 Year	rr_ExpenseExampleYear01	653
3 Years	rr_ExpenseExampleYear03	944
5 Years	rr_ExpenseExampleYear05	1,275
10 Years	rr_ExpenseExampleYear10	2,211
2007	rr_AnnualReturn2007	21.09%
2008	rr_AnnualReturn2008	(38.79%)
2009	rr_AnnualReturn2009	34.50%
2010	rr_AnnualReturn2010	10.60%
2011	rr_AnnualReturn2011	(12.43%)
2012	rr_AnnualReturn2012	14.53%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	24.03%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(21.57%)
1 Year	rr_AverageAnnualReturnYear01	8.54%
5 Years	rr_AverageAnnualReturnYear05	(2.85%)
Since Inception	rr_AverageAnnualReturnSinceInception	2.22%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 31, 2006
Investor, Institutional and R Shares | BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO | Investor B Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	4.50%	[3]
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.21%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.03%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.18%	[2]
1 Year	rr_ExpenseExampleYear01	671
3 Years	rr_ExpenseExampleYear03	1,035
5 Years	rr_ExpenseExampleYear05	1,379
10 Years	rr_ExpenseExampleYear10	2,365
1 Year	rr_ExpenseExampleNoRedemptionYear01	221
3 Years	rr_ExpenseExampleNoRedemptionYear03	685
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,179
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,365
1 Year	rr_AverageAnnualReturnYear01	9.11%
5 Years	rr_AverageAnnualReturnYear05	(2.93%)
Since Inception	rr_AverageAnnualReturnSinceInception	2.25%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 31, 2006
Investor, Institutional and R Shares | BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO | Investor C Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[4]
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.42%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.32%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.18%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.14%	[2]
1 Year	rr_ExpenseExampleYear01	317
3 Years	rr_ExpenseExampleYear03	689
5 Years	rr_ExpenseExampleYear05	1,207
10 Years	rr_ExpenseExampleYear10	2,627
1 Year	rr_ExpenseExampleNoRedemptionYear01	217
3 Years	rr_ExpenseExampleNoRedemptionYear03	689
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,207
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,627
1 Year	rr_AverageAnnualReturnYear01	12.68%
5 Years	rr_AverageAnnualReturnYear05	(2.57%)
Since Inception	rr_AverageAnnualReturnSinceInception	2.24%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 31, 2006
Investor, Institutional and R Shares | BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO | Institutional Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.35%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.25%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.19%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.06%	[2]
1 Year	rr_ExpenseExampleYear01	108
3 Years	rr_ExpenseExampleYear03	358
5 Years	rr_ExpenseExampleYear05	649
10 Years	rr_ExpenseExampleYear10	1,477
1 Year	rr_AverageAnnualReturnYear01	14.87%
5 Years	rr_AverageAnnualReturnYear05	(1.50%)
Since Inception	rr_AverageAnnualReturnSinceInception	3.31%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 31, 2006
Investor, Institutional and R Shares | BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO | Class R Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fees	rr_ManagementFeesOverAssets	0.90%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	0.50%
Other Expenses	rr_OtherExpensesOverAssets	0.40%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.80%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.08%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.72%	[2]
1 Year	rr_ExpenseExampleYear01	175
3 Years	rr_ExpenseExampleYear03	550
5 Years	rr_ExpenseExampleYear05	960
10 Years	rr_ExpenseExampleYear10	2,102
1 Year	rr_AverageAnnualReturnYear01	14.06%
5 Years	rr_AverageAnnualReturnYear05	(2.15%)
Since Inception	rr_AverageAnnualReturnSinceInception	2.63%
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 31, 2006
Investor, Institutional and R Shares | BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	8.38%
5 Years	rr_AverageAnnualReturnYear05	(2.91%)
Since Inception	rr_AverageAnnualReturnSinceInception	1.95%
Investor, Institutional and R Shares | BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions and Sale of Shares | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	5.77%
5 Years	rr_AverageAnnualReturnYear05	(2.39%)
Since Inception	rr_AverageAnnualReturnSinceInception	1.82%
Investor, Institutional and R Shares | BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO | MSCI All Country World Index (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	16.13%
5 Years	rr_AverageAnnualReturnYear05	(1.16%)
Since Inception	rr_AverageAnnualReturnSinceInception	2.85%

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] As described in the "Management of the Funds" section of the Fund's prospectus on pages 62-70, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.33% (for Investor A Shares), 2.18% (for Investor B Shares), 2.14% (for Investor C Shares), 1.06% (for Institutional Shares) and 1.72% (for Class R Shares) until February 1, 2015. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[3] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[4] There is no CDSC on Investor C Shares after one year.

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Service Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO

Fund Overview

Key Facts About BlackRock Health Sciences Opportunities Portfolio

Investment Objective

The investment objective of BlackRock Health Sciences Opportunities Portfolio (“Health Sciences Opportunities” or the “Fund”), one portfolio of BlackRock Funds^SM (the “Trust”), is to provide long-term growth of capital.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold Services Shares of Health Sciences Opportunities.

Annual Fund Operating Expenses
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Service Shares BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO
Management Fee		0.73%
Distribution and/or Service (12b-1) Fees		0.25%
Other Expenses		0.30%
Acquired Fund Fees and Expenses	[1]	0.01%
Total Annual Fund Operating Expenses	[1]	1.29%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Service Shares BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO	131	409	708	1,556

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 135% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Under normal market conditions, Health Sciences Opportunities invests at least 80% of total assets in equity securities, primarily common stock, of companies in health sciences and related industries. The health sciences sector can include companies in health care equipment and supplies, health care providers and services, biotechnology, and pharmaceuticals. Health sciences and related industries can include, but are not limited to, businesses involved in the development, production, and distribution or delivery of medical and pharmaceutical products and services, companies engaged in biotechnology and medical research and development, companies that may design, manufacture or distribute medical, dental and optical equipment and supplies, including diagnostic equipment, and companies that may also provide diagnostic services or operate health facilities and hospitals, or provide related administrative, management and financial support. The Fund will concentrate its investments (i.e., invest more than 25% of its assets) in health sciences or related industries, and may invest in companies located in non-U.S. countries.

The Fund reserves the right to invest up to 20% of total assets in other types of securities. These may include stocks of companies not associated with health sciences.

The Fund is classified as non-diversified under the Investment Company Act of 1940, as amended, which means that it can invest more of its assets in fewer companies than a diversified fund.

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in Health Sciences Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Concentration Risk — The Fund’s strategy of concentrating in health sciences and related companies means that its performance will be closely tied to the performance of a particular market segment. The Fund’s concentration in these companies may present more risks than if it were broadly diversified over numerous industries and sectors of the economy. A downturn in these companies would have a larger impact on the Fund than on a mutual fund that does not concentrate in such companies. At times, the performance of these companies will lag the performance of other industries or the broader market as a whole.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include:
  
  — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight.
  
  — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.
  
  — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position.
  
  — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries.
  
  — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws.
  
  — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments.
  
  — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments.

• Healthcare-Related Securities Risk — Many healthcare-related companies are smaller and less seasoned than companies in other sectors. Healthcare-related companies may also be strongly affected by scientific or technological developments and their products may quickly become obsolete. Many healthcare companies are heavily dependent on patent protection and the actual or perceived safety and efficiency of their products. The expiration of patents may adversely affect the profitability of these companies. Many healthcare companies are subject to extensive litigation based on product liability and similar claims. Finally, many healthcare-related companies offer products and services that are subject to governmental regulation and may be adversely affected by changes in governmental policies or laws. In March 2010, President Obama signed into law the Patient Protection and Affordable Care Act designed to reform the healthcare industry. The Fund cannot predict the impact of this legislation on healthcare-related companies or what healthcare-related proposals might be proposed or enacted in the future.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies.

• Non-Diversification Risk — The Fund is a non-diversified fund. Because the Fund may invest in securities of a smaller number of issuers, it may be more exposed to the risks associated with and developments affecting an individual issuer than a fund that invests more widely.

• Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.

Performance Information

On January 31, 2005, Health Sciences Opportunities reorganized with the State Street Research Health Sciences Fund (the “SSR Fund”), which had investment objectives and strategies substantially similar to the Fund. For periods prior to January 31, 2005, the chart and table show performance information for the SSR Fund. The performance of Service Shares for the period before January 28, 2005 is based on the performance of Investor A Shares, adjusted to reflect the class specific fees applicable to Service Shares at the time of such share class’ launch. This information may be considered when assessing the Fund’s performance, but does not represent the actual performance of Service Shares.

The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Standard & Poor’s (S&P) 500^® Index. The table also compares the Fund’s performance to that of the Russell 3000^® Health Care Index, which is relevant to the Fund because it has characteristics similar to the Fund’s investment strategies. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Service Shares
ANNUAL TOTAL RETURNS
BlackRock Health Sciences Opportunities Portfolio
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 34.69% (quarter ended June 30, 2003) and the lowest return for a quarter was –13.96% (quarter ended December 31, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Service Shares	1 Year	5 Years	10 Years
BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO	18.37%	6.64%	14.92%
BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO Return After Taxes on Distributions	16.93%	5.63%	13.95%
BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO Return After Taxes on Distributions and Sale of Shares	13.34%	5.41%	13.09%
BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO Russell 3000® Health Care Index (Reflects no deduction for fees, expenses or taxes)	19.32%	5.52%	7.13%
BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO S&P 500® Index (Reflects no deduction for fees, expenses or taxes)	16.00%	1.66%	7.10%

After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

[1] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

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Investor, Institutional and R Shares | BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO

Fund Overview

Key Facts About BlackRock Global Opportunities Portfolio

Investment Objective

The investment objective of BlackRock Global Opportunities Portfolio (“Global Opportunities” or the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is to provide long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of Global Opportunities. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 47 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Investor, Institutional and R Shares BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO	Investor A Shares		Investor B Shares		Investor C Shares		Institutional Shares	Class R Shares
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	5.25%		none		none		none	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	none	[1]	4.50%	[2]	1.00%	[3]	none	none

Annual Fund Operating Expenses
(expenses that you pay each year as a
percentage of the value of your investment)

Annual Fund Operating Expenses Investor, Institutional and R Shares BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO		Investor A Shares	Investor B Shares	Investor C Shares	Institutional Shares	Class R Shares
Management Fees		0.90%	0.90%	0.90%	0.90%	0.90%
Distribution (12b-1) and/or Service Fees		0.25%	1.00%	1.00%	none	0.50%
Other Expenses		0.37%	0.31%	0.42%	0.35%	0.40%
Total Annual Fund Operating Expenses		1.52%	2.21%	2.32%	1.25%	1.80%
Fee Waivers and/or Expense Reimbursements	[1]	(0.19%)	(0.03%)	(0.18%)	(0.19%)	(0.08%)
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[1]	1.33%	2.18%	2.14%	1.06%	1.72%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example Investor, Institutional and R Shares BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor A Shares	653	944	1,275	2,211
Investor B Shares	671	1,035	1,379	2,365
Investor C Shares	317	689	1,207	2,627
Institutional Shares	108	358	649	1,477
Class R Shares	175	550	960	2,102

You would pay the following expenses if you did not redeem your shares:

Expense Example, No Redemption Investor, Institutional and R Shares BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor B Shares	221	685	1,179	2,365
Investor C Shares	217	689	1,207	2,627

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 122% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Under normal conditions, Global Opportunities will invest at least 75% of its total assets in global equity securities of any market capitalization, selected for their above-average return potential. The Fund seeks to buy primarily common stock but may also invest in preferred stock and convertible securities. The Fund may invest up to 25% of its total assets in stocks of issuers in emerging market countries.

The Fund may invest up to 25% of its total assets in global fixed income securities, including corporate bonds, U.S. government debt securities, non-U.S. government and supranational debt securities, asset-backed securities, mortgage-backed securities, emerging market debt securities and non-investment grade debt securities (high yield or junk bonds). Investment in fixed income securities will be made on an opportunistic basis. Securities will be identified based on factors such as relative value and earnings estimate revisions.

From time to time, the Fund may invest in shares of companies through initial public offerings (“IPOs”). The Fund will invest in securities of non-U.S. issuers that can be U.S. dollar based or non-U.S. dollar based on a hedged or unhedged basis. The Fund may enter into currency transactions on a hedged or unhedged basis in order to seek total return.

The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies, or enter into foreign currency transactions, including swaps (collectively, commonly known as derivatives). The Fund typically uses derivatives as a substitute for taking a position in the underlying asset and/or as part of a strategy designed to reduce exposure to other risks, such as currency risk. The Fund may also use derivatives to enhance returns, in which case their use would involve leveraging risk. The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may also use forward foreign currency exchange contracts (obligations to buy or sell a currency at a set rate in the future).

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in Global Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock.

• Debt Securities Risk — Debt securities, such as bonds, involve credit risk. Credit risk is the risk that the borrower will not make timely payments of principal and interest. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. The degree of credit risk depends on the issuer’s financial condition and on the terms of the securities. Debt securities are also subject to interest rate risk. Interest rate risk is the risk that the value of a debt security may fall when interest rates rise. In general, the market price of debt securities with longer maturities will go up or down more in response to changes in interest rates than the market price of shorter term securities.

• Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives.

• Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include:
  
  — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight.
  
  — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.
  
  — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position.
  
  — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries.
  
  — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws.
  
  — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments.
  
  — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies.

• “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.

• Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.

Performance Information

The information shows you how Global Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the average annual total returns of each class of the Fund’s shares with that of the MSCI All Country World Index. Class R Shares commenced operations on September 12, 2011, therefore the returns in the table for Class R Shares prior to commencement date are based on the Fund’s Institutional Shares, adjusted to reflect the fees and expenses applicable to Class R Shares. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Investor A Shares
ANNUAL TOTAL RETURNS
BlackRock Global Opportunities Portfolio
As of 12/31

During the periods shown in the bar chart, the highest return for a quarter was 24.03% (quarter ended June 30, 2009) and the lowest return for a quarter was –21.57% (quarter ended December 31, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Investor, Institutional and R Shares BLACKROCK GLOBAL OPPORTUNITIES PORTFOLIO	1 Year	5 Years	Since Inception	Inception Date
Investor A	8.54%	(2.85%)	2.22%	Jan. 31, 2006
Investor A Return After Taxes on Distributions	8.38%	(2.91%)	1.95%
Investor A Return After Taxes on Distributions and Sale of Shares	5.77%	(2.39%)	1.82%
Investor B	9.11%	(2.93%)	2.25%	Jan. 31, 2006
Investor C	12.68%	(2.57%)	2.24%	Jan. 31, 2006
Institutional	14.87%	(1.50%)	3.31%	Jan. 31, 2006
Class R	14.06%	(2.15%)	2.63%	Jan. 31, 2006
MSCI All Country World Index (Reflects no deduction for fees, expenses or taxes)	16.13%	(1.16%)	2.85%

After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[3] There is no CDSC on Investor C Shares after one year.

[1] As described in the "Management of the Funds" section of the Fund's prospectus on pages 62-70, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.33% (for Investor A Shares), 2.18% (for Investor B Shares), 2.14% (for Investor C Shares), 1.06% (for Institutional Shares) and 1.72% (for Class R Shares) until February 1, 2015. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Service Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock Health Sciences Opportunities Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock Health Sciences Opportunities Portfolio (“Health Sciences Opportunities” or the “Fund”), one portfolio of BlackRock FundsSM (the “Trust”), is to provide long-term growth of capital.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Services Shares of Health Sciences Opportunities.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 135% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	135.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund’s most recent annual report which does not include the Acquired Fund Fees and Expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, Health Sciences Opportunities invests at least 80% of total assets in equity securities, primarily common stock, of companies in health sciences and related industries. The health sciences sector can include companies in health care equipment and supplies, health care providers and services, biotechnology, and pharmaceuticals. Health sciences and related industries can include, but are not limited to, businesses involved in the development, production, and distribution or delivery of medical and pharmaceutical products and services, companies engaged in biotechnology and medical research and development, companies that may design, manufacture or distribute medical, dental and optical equipment and supplies, including diagnostic equipment, and companies that may also provide diagnostic services or operate health facilities and hospitals, or provide related administrative, management and financial support. The Fund will concentrate its investments (i.e., invest more than 25% of its assets) in health sciences or related industries, and may invest in companies located in non-U.S. countries. The Fund reserves the right to invest up to 20% of total assets in other types of securities. These may include stocks of companies not associated with health sciences. The Fund is classified as non-diversified under the Investment Company Act of 1940, as amended, which means that it can invest more of its assets in fewer companies than a diversified fund.
Strategy Portfolio Concentration [Text]	rr_StrategyPortfolioConcentration	The Fund will concentrate its investments (i.e., invest more than 25% of its assets) in health sciences or related industries, and may invest in companies located in non-U.S. countries.
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in Health Sciences Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Concentration Risk — The Fund’s strategy of concentrating in health sciences and related companies means that its performance will be closely tied to the performance of a particular market segment. The Fund’s concentration in these companies may present more risks than if it were broadly diversified over numerous industries and sectors of the economy. A downturn in these companies would have a larger impact on the Fund than on a mutual fund that does not concentrate in such companies. At times, the performance of these companies will lag the performance of other industries or the broader market as a whole. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include: — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight. — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio. — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries. — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws. — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments. — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments. Healthcare-Related Securities Risk — Many healthcare-related companies are smaller and less seasoned than companies in other sectors. Healthcare-related companies may also be strongly affected by scientific or technological developments and their products may quickly become obsolete. Many healthcare companies are heavily dependent on patent protection and the actual or perceived safety and efficiency of their products. The expiration of patents may adversely affect the profitability of these companies. Many healthcare companies are subject to extensive litigation based on product liability and similar claims. Finally, many healthcare-related companies offer products and services that are subject to governmental regulation and may be adversely affected by changes in governmental policies or laws. In March 2010, President Obama signed into law the Patient Protection and Affordable Care Act designed to reform the healthcare industry. The Fund cannot predict the impact of this legislation on healthcare-related companies or what healthcare-related proposals might be proposed or enacted in the future. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies. Non-Diversification Risk — The Fund is a non-diversified fund. Because the Fund may invest in securities of a smaller number of issuers, it may be more exposed to the risks associated with and developments affecting an individual issuer than a fund that invests more widely. Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	Non-Diversification Risk — The Fund is a non-diversified fund. Because the Fund may invest in securities of a smaller number of issuers, it may be more exposed to the risks associated with and developments affecting an individual issuer than a fund that invests more widely.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	On January 31, 2005, Health Sciences Opportunities reorganized with the State Street Research Health Sciences Fund (the “SSR Fund”), which had investment objectives and strategies substantially similar to the Fund. For periods prior to January 31, 2005, the chart and table show performance information for the SSR Fund. The performance of Service Shares for the period before January 28, 2005 is based on the performance of Investor A Shares, adjusted to reflect the class specific fees applicable to Service Shares at the time of such share class’ launch. This information may be considered when assessing the Fund’s performance, but does not represent the actual performance of Service Shares. The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Standard & Poor’s (S&P) 500® Index. The table also compares the Fund’s performance to that of the Russell 3000® Health Care Index, which is relevant to the Fund because it has characteristics similar to the Fund’s investment strategies. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Service Shares ANNUAL TOTAL RETURNS BlackRock Health Sciences Opportunities Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the ten-year period shown in the bar chart, the highest return for a quarter was 34.69% (quarter ended June 30, 2003) and the lowest return for a quarter was –13.96% (quarter ended December 31, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Service Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Service Shares
Risk/Return:	rr_RiskReturnAbstract
Management Fee	rr_ManagementFeesOverAssets	0.73%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.30%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.29%	[1]
1 Year	rr_ExpenseExampleYear01	131
3 Years	rr_ExpenseExampleYear03	409
5 Years	rr_ExpenseExampleYear05	708
10 Years	rr_ExpenseExampleYear10	1,556
2003	rr_AnnualReturn2003	66.64%
2004	rr_AnnualReturn2004	14.56%
2005	rr_AnnualReturn2005	16.83%
2006	rr_AnnualReturn2006	8.31%
2007	rr_AnnualReturn2007	20.41%
2008	rr_AnnualReturn2008	(19.34%)
2009	rr_AnnualReturn2009	27.25%
2010	rr_AnnualReturn2010	7.12%
2011	rr_AnnualReturn2011	5.98%
2012	rr_AnnualReturn2012	18.37%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	34.69%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(13.96%)
1 Year	rr_AverageAnnualReturnYear01	18.37%
5 Years	rr_AverageAnnualReturnYear05	6.64%
10 Years	rr_AverageAnnualReturnYear10	14.92%
Service Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions | Service Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	16.93%
5 Years	rr_AverageAnnualReturnYear05	5.63%
10 Years	rr_AverageAnnualReturnYear10	13.95%
Service Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions and Sale of Shares | Service Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	13.34%
5 Years	rr_AverageAnnualReturnYear05	5.41%
10 Years	rr_AverageAnnualReturnYear10	13.09%
Service Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | Russell 3000® Health Care Index (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	19.32%
5 Years	rr_AverageAnnualReturnYear05	5.52%
10 Years	rr_AverageAnnualReturnYear10	7.13%
Service Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO | S&P 500® Index (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	16.00%
5 Years	rr_AverageAnnualReturnYear05	1.66%
10 Years	rr_AverageAnnualReturnYear10	7.10%

[1] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Investor and Institutional | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock International Opportunities Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock International Opportunities Portfolio (“International Opportunities” or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to seek long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold shares of International Opportunities. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 47 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	February 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 99% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	99.00%
Expenses Deferred Charges [Text Block]	rr_ExpensesDeferredChargesTextBlock	A contingent deferred sales charge (“CDSC”) of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.
Expense Breakpoint Discounts [Text]	rr_ExpenseBreakpointDiscounts	You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”).
Expense Breakpoint, Minimum Investment Required [Amount]	rr_ExpenseBreakpointMinimumInvestmentRequiredAmount	25,000
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund’s most recent annual report which does not include the Acquired Fund Fees and Expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	You would pay the following expenses if you did not redeem your shares:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, International Opportunities invests at least 80% of its net assets in equity securities issued by foreign companies of any market capitalization. The Fund may invest up to 40% of its net assets in stocks of issuers in emerging market countries. The Fund seeks to buy primarily common stock but can also invest in preferred stock and convertible securities. From time to time the Fund may invest in shares of companies through initial public offerings (“IPOs”). The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies, or enter into foreign currency transactions, including swaps (collectively, commonly known as derivatives). The Fund typically uses derivatives as a substitute for taking a position in the underlying asset and/or as part of a strategy designed to reduce exposure to other risks, such as currency risk. The Fund may also use derivatives to enhance returns, in which case their use would involve leveraging risk. The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may also use forward foreign currency exchange contracts (obligations to buy or sell a currency at a set rate in the future).
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in International Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock. Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives. Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include: — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight. — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio. — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries. — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws. — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments. — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies. “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering. Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The information shows you how International Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the average annual total returns of each class of the Fund’s shares with that of the MSCI All Country World Index Ex-U.S. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how International Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Investor A Shares ANNUAL TOTAL RETURNS BlackRock International Opportunities Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the ten-year period shown in the bar chart, the highest return for a quarter was 28.03% (quarter ended June 30, 2009) and the lowest return for a quarter was –24.50% (quarter ended September 30, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C and Institutional Shares will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C and Institutional Shares will vary.
Investor and Institutional | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	5.25%
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none	[1]
Management Fees	rr_ManagementFeesOverAssets	0.98%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.34%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.58%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.58%	[3]
1 Year	rr_ExpenseExampleYear01	677
3 Years	rr_ExpenseExampleYear03	998
5 Years	rr_ExpenseExampleYear05	1,340
10 Years	rr_ExpenseExampleYear10	2,305
2003	rr_AnnualReturn2003	48.59%
2004	rr_AnnualReturn2004	25.53%
2005	rr_AnnualReturn2005	31.80%
2006	rr_AnnualReturn2006	31.46%
2007	rr_AnnualReturn2007	18.13%
2008	rr_AnnualReturn2008	(43.34%)
2009	rr_AnnualReturn2009	36.59%
2010	rr_AnnualReturn2010	11.42%
2011	rr_AnnualReturn2011	(14.42%)
2012	rr_AnnualReturn2012	18.02%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	28.03%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(24.50%)
1 Year	rr_AverageAnnualReturnYear01	11.83%
5 Years	rr_AverageAnnualReturnYear05	(3.77%)
10 Years	rr_AverageAnnualReturnYear10	11.98%
Investor and Institutional | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | Investor B Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	4.50%	[4]
Management Fees	rr_ManagementFeesOverAssets	0.98%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.43%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.42%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.42%	[3]
1 Year	rr_ExpenseExampleYear01	695
3 Years	rr_ExpenseExampleYear03	1,105
5 Years	rr_ExpenseExampleYear05	1,491
10 Years	rr_ExpenseExampleYear10	2,548
1 Year	rr_ExpenseExampleNoRedemptionYear01	245
3 Years	rr_ExpenseExampleNoRedemptionYear03	755
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,291
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,548
1 Year	rr_AverageAnnualReturnYear01	12.50%
5 Years	rr_AverageAnnualReturnYear05	(3.88%)
10 Years	rr_AverageAnnualReturnYear10	11.89%
Investor and Institutional | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | Investor C Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[5]
Management Fees	rr_ManagementFeesOverAssets	0.98%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.36%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.35%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.35%	[3]
1 Year	rr_ExpenseExampleYear01	338
3 Years	rr_ExpenseExampleYear03	733
5 Years	rr_ExpenseExampleYear05	1,255
10 Years	rr_ExpenseExampleYear10	2,686
1 Year	rr_ExpenseExampleNoRedemptionYear01	238
3 Years	rr_ExpenseExampleNoRedemptionYear03	733
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,255
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,686
1 Year	rr_AverageAnnualReturnYear01	16.15%
5 Years	rr_AverageAnnualReturnYear05	(3.47%)
10 Years	rr_AverageAnnualReturnYear10	11.74%
Investor and Institutional | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | Institutional Shares
Risk/Return:	rr_RiskReturnAbstract
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fees	rr_ManagementFeesOverAssets	0.98%
Distribution (12b-1) and/or Service Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.31%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[2]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.30%	[2]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[3]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.30%	[3]
1 Year	rr_ExpenseExampleYear01	132
3 Years	rr_ExpenseExampleYear03	412
5 Years	rr_ExpenseExampleYear05	713
10 Years	rr_ExpenseExampleYear10	1,568
1 Year	rr_AverageAnnualReturnYear01	18.38%
5 Years	rr_AverageAnnualReturnYear05	(2.45%)
10 Years	rr_AverageAnnualReturnYear10	12.95%
Investor and Institutional | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	11.59%
5 Years	rr_AverageAnnualReturnYear05	(3.81%)
10 Years	rr_AverageAnnualReturnYear10	11.19%
Investor and Institutional | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions and Sale of Shares | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	8.00%
5 Years	rr_AverageAnnualReturnYear05	(3.07%)
10 Years	rr_AverageAnnualReturnYear10	10.68%
Investor and Institutional | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO | MSCI All Country World Index Ex-U.S. (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	16.83%
5 Years	rr_AverageAnnualReturnYear05	(2.89%)
10 Years	rr_AverageAnnualReturnYear10	9.74%

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

[3] As described in the "Management of the Funds" section of the Fund's prospectus on pages 62-70, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.98% (for Investor A Shares), 2.75% (for Investor B and Investor C Shares) and 1.49% (for Institutional Shares) until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[4] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[5] There is no CDSC on Investor C Shares after one year.

XML

Document and Entity Information	12 Months Ended
	Jan. 28, 2013
Risk/Return:
Document Type	Other
Document Period End Date	Sep. 30, 2012
Registrant Name	BLACKROCK FUNDS
Central Index Key	0000844779
Amendment Flag	false
Document Creation Date	Feb. 04, 2013
Document Effective Date	Feb. 04, 2013
Prospectus Date	Jan. 28, 2013

XML

Investor, Institutional and R Shares | BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO

Fund Overview

Key Facts About BlackRock Health Sciences Opportunities Portfolio

Investment Objective

The investment objective of BlackRock Health Sciences Opportunities Portfolio (“Health Sciences Opportunities” or the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is to provide long-term growth of capital.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of Health Sciences Opportunities. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 47 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Investor, Institutional and R Shares BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO	Investor A Shares		Investor B Shares		Investor C Shares		Institutional Shares	Class R Shares
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	5.25%		none		none		none	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	none	[1]	4.50%	[2]	1.00%	[3]	none	none

Annual Fund Operating Expenses
(expenses that you pay each year as
a percentage of the value of your investment)

Annual Fund Operating Expenses Investor, Institutional and R Shares BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO		Investor A Shares	Investor B Shares	Investor C Shares	Institutional Shares	Class R Shares
Management Fees		0.73%	0.73%	0.73%	0.73%	0.73%
Distribution (12b-1) and/or Service Fees		0.25%	1.00%	1.00%	none	0.50%
Other Expenses		0.31%	0.34%	0.28%	0.25%	0.47%
Acquired Fund Fees and Expenses	[1]	0.01%	0.01%	0.01%	0.01%	0.01%
Total Annual Fund Operating Expenses	[1]	1.30%	2.08%	2.02%	0.99%	1.71%
Fee Waivers and/or Expense Reimbursements	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[2]	1.30%	2.08%	2.02%	0.99%	1.71%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example Investor, Institutional and R Shares BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor A Shares	650	915	1,200	2,010
Investor B Shares	661	1,002	1,319	2,211
Investor C Shares	305	634	1,088	2,348
Institutional Shares	101	315	547	1,213
Class R Shares	174	539	928	2,019

You would pay the following expenses if you did not redeem your shares:

Expense Example, No Redemption Investor, Institutional and R Shares BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor B Shares	211	652	1,119	2,211
Investor C Shares	205	634	1,088	2,348

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 135% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Under normal market conditions, Health Sciences Opportunities invests at least 80% of total assets in equity securities, primarily common stock, of companies in health sciences and related industries. The health sciences sector can include companies in health care equipment and supplies, health care providers and services, biotechnology, and pharmaceuticals. Health sciences and related industries can include, but are not limited to, businesses involved in the development, production, and distribution or delivery of medical and pharmaceutical products and services, companies engaged in biotechnology and medical research and development, companies that may design, manufacture or distribute medical, dental and optical equipment and supplies, including diagnostic equipment, and companies that may also provide diagnostic services or operate health facilities and hospitals, or provide related administrative, management and financial support. The Fund will concentrate its investments (i.e., invest more than 25% of its assets) in health sciences or related industries, and may invest in companies located in non-U.S. countries.

The Fund reserves the right to invest up to 20% of total assets in other types of securities. These may include stocks of companies not associated with health sciences.

The Fund is classified as non-diversified under the Investment Company Act of 1940, as amended, which means that it can invest more of its assets in fewer companies than a diversified fund.

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in Health Sciences Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Concentration Risk — The Fund’s strategy of concentrating in health sciences and related companies means that its performance will be closely tied to the performance of a particular market segment. The Fund’s concentration in these companies may present more risks than if it were broadly diversified over numerous industries and sectors of the economy. A downturn in these companies would have a larger impact on the Fund than on a mutual fund that does not concentrate in such companies. At times, the performance of these companies will lag the performance of other industries or the broader market as a whole.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include:
  
  —  The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight.
  
  — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.
  
  — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position.
  
  — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries.
  
  — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws.
  
  — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments.
  
  — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments.

• Healthcare-Related Securities Risk — Many healthcare-related companies are smaller and less seasoned than companies in other sectors. Healthcare-related companies may also be strongly affected by scientific or technological developments and their products may quickly become obsolete. Many healthcare companies are heavily dependent on patent protection and the actual or perceived safety and efficiency of their products. The expiration of patents may adversely affect the profitability of these companies. Many healthcare companies are subject to extensive litigation based on product liability and similar claims. Finally, many healthcare-related companies offer products and services that are subject to governmental regulation and may be adversely affected by changes in governmental policies or laws. In March 2010, President Obama signed into law the Patient Protection and Affordable Care Act designed to reform the healthcare industry. The Fund cannot predict the impact of this legislation on healthcare-related companies or what healthcare-related proposals might be proposed or enacted in the future.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies.

• Non-Diversification Risk — The Fund is a non-diversified fund. Because the Fund may invest in securities of a smaller number of issuers, it may be more exposed to the risks associated with and developments affecting an individual issuer than a fund that invests more widely.

• Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.

Performance Information

On January 31, 2005, Health Sciences Opportunities reorganized with the State Street Research Health Sciences Fund (the “SSR Fund”). For periods prior to January 31, 2005, the chart and table show performance information for the SSR Fund, which had investment objectives and strategies substantially similar to the Fund. The performance of Investor B and Investor C Shares for the period before they were launched is based on the performance of Investor A Shares, adjusted to reflect the class specific fees applicable to Investor B and Investor C Shares, respectively, at the time of such share class’ launch. Class R Shares commenced operations on September 12, 2011, therefore the returns in the table for Class R Shares prior to commencement date are based on the Fund’s Institutional Shares, adjusted to reflect the fees and expenses applicable to Class R Shares. This information may be considered when assessing the Fund’s performance, but does not represent the actual performance of these share classes.

The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the Standard & Poor’s (“S&P”) 500^® Index. The table also compares the Fund’s performance to that of the Russell 3000^® Health Care Index, which is relevant to the Fund because it has characteristics similar to the Fund’s investment strategies. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Investor A Shares
ANNUAL TOTAL RETURNS
BlackRock Health Sciences Opportunities Portfolio
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 34.69% (quarter ended June 30, 2003) and the lowest return for a quarter was –13.97% (quarter ended December 31, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Investor, Institutional and R Shares BLACKROCK HEALTH SCIENCES OPPORTUNITIES PORTFOLIO	1 Year	5 Years	10 Years
Investor A	12.17%	5.51%	14.28%
Investor A Return After Taxes On Distributions	10.80%	4.51%	13.32%
Investor A Return After Taxes On Distributions And Sale Of Shares	9.25%	4.42%	12.48%
Investor B	12.99%	5.50%	14.19%
Investor C	16.58%	5.89%	14.08%
Institutional	18.77%	6.99%	15.25%
Class R	17.92%	6.17%	14.35%
Russell 3000® Health Care Index (Reflects no deduction for fees, expenses or taxes)	19.32%	5.52%	7.13%
S&P 500® Index (Reflects no deduction for fees, expenses or taxes)	16.00%	1.66%	7.10%

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[3] There is no CDSC on Investor C Shares after one year.

[1] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

[2] As described in the "Management of the Funds" section of the Fund's prospectus on pages 62-70, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.81% for Class R Shares until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

XML

Service Shares | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO

Fund Overview

Key Facts About BlackRock International Opportunities Portfolio

Investment Objective

The investment objective of BlackRock International Opportunities Portfolio (“International Opportunities” or the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is to seek long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold Services Shares of International Opportunities.

Annual Fund Operating Expenses
(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses		Service Shares BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO
Management Fee		0.98%
Distribution and/or Service (12b-1) Fees		0.25%
Other Expenses		0.67%
Acquired Fund Fees and Expenses	[1]	0.01%
Total Annual Fund Operating Expenses	[1]	1.91%
Fee Waivers and/or Expense Reimbursements	[2]	(0.10%)
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[2]	1.81%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example (USD $)	1 Year	3 Years	5 Years	10 Years
Service Shares BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO	184	590	1,022	2,225

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 99% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Under normal market conditions, International Opportunities invests at least 80% of its net assets in equity securities issued by foreign companies of any market capitalization. The Fund may invest up to 40% of its net assets in stocks of issuers in emerging market countries.

The Fund seeks to buy primarily common stock but can also invest in preferred stock and convertible securities. From time to time the Fund may invest in shares of companies through initial public offerings (“IPOs”).

The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies, or enter into foreign currency transactions, including swaps (collectively, commonly known as derivatives). The Fund typically uses derivatives as a substitute for taking a position in the underlying asset and/or as part of a strategy designed to reduce exposure to other risks, such as currency risk. The Fund may also use derivatives to enhance returns, in which case their use would involve leveraging risk. The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may also use forward foreign currency exchange contracts (obligations to buy or sell a currency at a set rate in the future).

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in International Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock.

• Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives.

• Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative.
  Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include:
  
  — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight.
  
  — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.
  
  — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position.
  
  — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries.
  
  — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws.
  
  — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments.
  
  — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies.

• “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.

• Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.

Performance Information

The information shows you how International Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the MSCI All Country World Index Ex-U.S. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Service Shares
ANNUAL TOTAL RETURNS
BlackRock International Opportunities Portfolio
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 28.04% (quarter ended June 30, 2009) and the lowest return for a quarter was –24.50% (quarter ended September 30, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Service Shares	1 Year	5 Years	10 Years
BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO	17.77%	(2.83%)	12.57%
BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO Return After Taxes on Distributions	17.56%	(2.91%)	11.75%
BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO Return After Taxes on Distributions and Sale of Shares	11.82%	(2.35%)	11.19%
BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO MSCI All Country World Index Ex-U.S (Reflects no deduction for fees, expenses or taxes)	16.83%	(2.89%)	9.74%

After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.

[1] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

[2] As described in the "Management of the Funds" section of the Fund's prospectus on pages 40-46, BlackRock Advisors, LLC ("BlackRock") has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 1.80% of average daily net assets until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

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Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Jan. 28, 2013
Service Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock Science & Technology Opportunities Portfolio
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock Science & Technology Opportunities Portfolio (“Science & Technology Opportunities” or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to provide long-term capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses of the Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Services Shares of Science & Technology Opportunities.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	February 1, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover:
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 320% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	320.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund’s most recent annual report which does not include the Acquired Fund Fees and Expenses.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example:
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, Science & Technology Opportunities invests at least 80% of its net assets in equity securities issued by U.S. and non-U.S. science and technology companies in all market capitalization ranges, selected for their rapid and sustainable growth potential from the development, advancement and use of science and/or use of technology. The Fund may invest up to 25% of its net assets in emerging market countries. Some of the industries likely to be represented in the Fund’s portfolio holdings include: application software, IT consulting and services, internet software and services, networking equipment, telecom equipment, computer hardware, computer storage and peripherals, electronic equipment and instruments, semiconductors and equipment, aerospace and defense, electrical components and equipment, biotechnology, pharmaceuticals, healthcare equipment and supplies, healthcare distribution and services, healthcare facilities, industrial gases, specialty chemicals, advanced materials, internet and catalog retail, integrated telecom services, alternative carriers and wireless telecommunication services. The Fund seeks to invest primarily in common stock but may also invest in preferred stock and convertible securities. The Fund may also invest in Rule 144A securities, which are privately placed securities purchased by qualified institutional buyers. From time to time the Fund may invest in shares of companies through initial public offerings (“IPOs”). The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies, or enter into foreign currency transactions, including swaps (collectively, commonly known as derivatives). The Fund typically uses derivatives as a substitute for taking a position in the underlying asset and/or as part of a strategy designed to reduce exposure to other risks, such as currency risk. The Fund may also use derivatives to enhance returns, in which case their use would involve leveraging risk. The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may also use forward foreign currency exchange contracts (obligations to buy or sell a currency at a set rate in the future).
Risk [Heading]	rr_RiskHeading	Principal Risks of Investing in the Fund
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	Risk is inherent in all investing. The value of your investment in Science & Technology Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund. Concentration Risk — The Fund’s strategy of concentrating in science and technology and related companies means that its performance will be closely tied to the performance of a particular market segment. The Fund’s concentration in these companies may present more risks than if it were broadly diversified over numerous industries and sectors of the economy. A downturn in these companies would have a larger impact on the Fund than on a mutual fund that does not concentrate in such companies. At times, the performance of these companies will lag the performance of other industries or the broader market as a whole. Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock. Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives. Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets. Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include: — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight. — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio. — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries. — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws. — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments. — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments. Geographic Concentration Risk — From time to time the Fund may invest a substantial amount of its assets in issuers located in a single country or a limited number of countries. If the Fund concentrates its investments in this manner, it assumes the risk that economic, political and social conditions in those countries will have a significant impact on its investment performance. The Fund’s investment performance may also be more volatile if it concentrates its investments in certain countries, especially emerging market countries. Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage. Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies. “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering. Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies. Technology Securities Risk — Certain technology related companies may face special risks that their products or services may not prove to be commercially successful. Technology related companies are also strongly affected by worldwide scientific or technological developments. As a result, their products may rapidly become obsolete. Such companies are also often subject to governmental regulation and may, therefore, be adversely affected by governmental policies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The information shows you how Science & Technology Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the NYSE Arca Tech 100 IndexSM. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The information shows you how Science & Technology Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As with all such investments, past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading]	rr_BarChartHeading	Service Shares ANNUAL TOTAL RETURNS BlackRock Science & Technology Opportunities Portfolio As of 12/31
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the ten-year period shown in the bar chart, the highest return for a quarter was 30.03% (quarter ended June 30, 2003) and the lowest return for a quarter was –22.21% (quarter ended December 31, 2008).
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/12 Average Annual Total Returns
Performance Table Does Reflect Sales Loads	rr_PerformanceTableDoesReflectSalesLoads	However, the table includes all applicable fees and sales charges.
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts.
Service Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | Service Shares
Risk/Return:	rr_RiskReturnAbstract
Management Fee	rr_ManagementFeesOverAssets	0.90%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.42%
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.01%	[1]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.58%	[1]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets		[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.58%	[2]
1 Year	rr_ExpenseExampleYear01	161
3 Years	rr_ExpenseExampleYear03	499
5 Years	rr_ExpenseExampleYear05	860
10 Years	rr_ExpenseExampleYear10	1,878
2003	rr_AnnualReturn2003	58.58%
2004	rr_AnnualReturn2004	2.50%
2005	rr_AnnualReturn2005	11.20%
2006	rr_AnnualReturn2006	7.74%
2007	rr_AnnualReturn2007	19.11%
2008	rr_AnnualReturn2008	(39.82%)
2009	rr_AnnualReturn2009	56.33%	[3]
2010	rr_AnnualReturn2010	18.02%
2011	rr_AnnualReturn2011	(11.17%)
2012	rr_AnnualReturn2012	7.38%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	30.03%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(22.21%)
1 Year	rr_AverageAnnualReturnYear01	7.38%
5 Years	rr_AverageAnnualReturnYear05	1.16%	[3]
10 Years	rr_AverageAnnualReturnYear10	9.40%	[3]
Service Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions | Service Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	7.38%
5 Years	rr_AverageAnnualReturnYear05	1.16%	[3]
10 Years	rr_AverageAnnualReturnYear10	9.40%	[3]
Service Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | Return After Taxes on Distributions and Sale of Shares | Service Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	4.80%
5 Years	rr_AverageAnnualReturnYear05	0.99%	[3]
10 Years	rr_AverageAnnualReturnYear10	8.39%	[3]
Service Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO | NYSE Arca Tech 100 Index℠ (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	21.46%
5 Years	rr_AverageAnnualReturnYear05	7.62%	[3]
10 Years	rr_AverageAnnualReturnYear10	11.69%	[3]

[1] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

[2] As described in the "Management of the Funds" section of the Fund's prospectus on pages 40-46, BlackRock Advisors, LLC ("BlackRock") has contractually agreed to waive or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 1.78% of average daily net assets until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[3] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in a settlement of litigation.

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Investor, Institutional and R Shares | BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO

Fund Overview

Key Facts About BlackRock Science & Technology Opportunities Portfolio

Investment Objective

The investment objective of BlackRock Science & Technology Opportunities Portfolio (“Science & Technology Opportunities” or the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is to provide long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of Science & Technology Opportunities. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 47 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Investor, Institutional and R Shares BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO	Investor A Shares		Investor B Shares		Investor C Shares		Institutional Shares	Class R Shares
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	5.25%		none		none		none	none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	none	[1]	4.50%	[2]	1.00%	[3]	none	none

Annual Fund Operating Expenses
(expenses that are deducted from Fund assets)

Annual Fund Operating Expenses Investor, Institutional and R Shares BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO		Investor A Shares	Investor B Shares	Investor C Shares	Institutional Shares	Class R Shares
Management Fees		0.90%	0.90%	0.90%	0.90%	0.90%
Distribution (12b-1) and/or Service Fees		0.25%	1.00%	1.00%	none	0.50%
Other Expenses		0.57%	0.62%	0.70%	0.55%	0.60%
Acquired Fund Fees and Expenses	[1]	0.01%	0.01%	0.01%	0.01%	0.01%
Total Annual Fund Operating Expenses	[1]	1.73%	2.53%	2.61%	1.46%	2.01%
Fee Waivers and/or Expense Reimbursements	[2]				(0.06%)
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[2]	1.73%	2.53%	2.61%	1.40%	2.01%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example Investor, Institutional and R Shares BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor A Shares	692	1,041	1,414	2,459
Investor B Shares	706	1,138	1,545	2,670
Investor C Shares	364	811	1,385	2,944
Institutional Shares	143	456	792	1,741
Class R Shares	204	630	1,083	2,338

You would pay the following expenses if you did not redeem your shares:

Expense Example, No Redemption Investor, Institutional and R Shares BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor B Shares	256	788	1,345	2,670
Investor C Shares	264	811	1,385	2,944

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 320% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Under normal market conditions, Science & Technology Opportunities invests at least 80% of its net assets in equity securities issued by U.S. and non-U.S. science and technology companies in all market capitalization ranges, selected for their rapid and sustainable growth potential from the development, advancement and use of science and/or use of technology. The Fund may invest up to 25% of its net assets in emerging market countries.

Some of the industries likely to be represented in the Fund’s portfolio holdings include: application software, IT consulting and services, internet software and services, networking equipment, telecom equipment, computer hardware, computer storage and peripherals, electronic equipment and instruments, semiconductors and equipment, aerospace and defense, electrical components and equipment, biotechnology, pharmaceuticals, healthcare equipment and supplies, healthcare distribution and services, healthcare facilities, industrial gases, specialty chemicals, advanced materials, internet and catalog retail, integrated telecom services, alternative carriers and wireless telecommunication services.

The Fund seeks to invest primarily in common stock but may also invest in preferred stock and convertible securities. The Fund may also invest in Rule 144A securities, which are privately placed securities purchased by qualified institutional buyers. From time to time the Fund may invest in shares of companies through initial public offerings (“IPOs”).

The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies, or enter into foreign currency transactions, including swaps (collectively, commonly known as derivatives). The Fund typically uses derivatives as a substitute for taking a position in the underlying asset and/or as part of a strategy designed to reduce exposure to other risks, such as currency risk. The Fund may also use derivatives to enhance returns, in which case their use would involve leveraging risk. The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may also use forward foreign currency exchange contracts (obligations to buy or sell a currency at a set rate in the future).

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in Science & Technology Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Concentration Risk — The Fund’s strategy of concentrating in science and technology and related companies means that its performance will be closely tied to the performance of a particular market segment. The Fund’s concentration in these companies may present more risks than if it were broadly diversified over numerous industries and sectors of the economy. A downturn in these companies would have a larger impact on the Fund than on a mutual fund that does not concentrate in such companies. At times, the performance of these companies will lag the performance of other industries or the broader market as a whole.

• Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock.

• Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives.

• Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative.
  Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include:
  
  — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight.
  
  — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.
  
  — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position.
  
  — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries.
  
  — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws.
  
  — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments.
  
  — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments.

• Geographic Concentration Risk — From time to time the Fund may invest a substantial amount of its assets in issuers located in a single country or a limited number of countries. If the Fund concentrates its investments in this manner, it assumes the risk that economic, political and social conditions in those countries will have a significant impact on its investment performance. The Fund’s investment performance may also be more volatile if it concentrates its investments in certain countries, especially emerging market countries.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies.

• “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.

• Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.

• Technology Securities Risk — Certain technology related companies may face special risks that their products or services may not prove to be commercially successful. Technology related companies are also strongly affected by worldwide scientific or technological developments. As a result, their products may rapidly become obsolete. Such companies are also often subject to governmental regulation and may, therefore, be adversely affected by governmental policies.

Performance Information

The information shows you how Science & Technology Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the NYSE Arca Tech 100 Index^SM. The returns for Class R Shares prior to October 2, 2006, the commencement of operations of Class R Shares, are based upon performance of the Fund’s Institutional Shares. The returns for Class R Shares, however, are adjusted to reflect the class-specific fees applicable to Class R Shares at the time of such share class’ launch. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Investor A Shares
ANNUAL TOTAL RETURNS
BlackRock Science & Technology Opportunities Portfolio
As of 12/31

During the periods shown in the bar chart, the highest return for a quarter was 29.92% (quarter ended June 30, 2003) and the lowest return for a quarter was –22.29% (quarter ended December 31, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Investor, Institutional and R Shares BLACKROCK SCIENCE & TECHNOLOGY OPPORTUNITIES PORTFOLIO	1 Year	5 Years		10 Years
Investor A	1.66%	(0.02%)	[1]	8.70%	[1]
Investor A Return After Taxes on Distributions	1.66%	(0.02%)	[1]	8.70%	[1]
Investor A Return After Taxes on Distributions and Sale of Shares	1.08%	(0.02%)	[1]	7.74%	[1]
Investor B	1.94%	(0.23%)	[1]	8.57%	[1]
Investor C	5.31%	0.17%	[1]	8.36%	[1]
Institutional	7.57%	1.43%	[1]	9.72%	[1]
Class R	6.96%	0.72%	[1]	8.92%	[1]
NYSE Arca Tech 100 Index℠ (Reflects no deduction for fees, expenses or taxes)	21.46%	7.62%	[1]	11.69%	[1]

After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C, Institutional and Class R Shares will vary.

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[3] There is no CDSC on Investor C Shares after one year.

[1] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

[2] As described in the "Management of the Funds" section of the Fund's prospectus on pages 62-70, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.80% (for Investor A Shares), 2.73% (for Investor B and Investor C Shares), 1.39% (for Institutional Shares) and 2.57% (for Class R Shares) until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in a settlement of litigation.

[1] A portion of the Fund's total return was attributable to proceeds received in the fiscal year ended September 30, 2009 in a settlement of litigation.

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Investor and Institutional | BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO

Fund Overview

Key Facts About BlackRock International Opportunities Portfolio

Investment Objective

The investment objective of BlackRock International Opportunities Portfolio (“International Opportunities” or the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is to seek long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of International Opportunities. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”). More information about these and other discounts is available from your financial professional and in the “Details About the Share Classes” section on page 47 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-58 of the Fund’s statement of additional information.

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Investor and Institutional BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO	Investor A Shares		Investor B Shares		Investor C Shares		Institutional Shares
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price)	5.25%		none		none		none
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower)	none	[1]	4.50%	[2]	1.00%	[3]	none

Annual Fund Operating Expenses
(expenses that you pay each year as a
percentage of the value of your investment)

Annual Fund Operating Expenses Investor and Institutional BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO		Investor A Shares	Investor B Shares	Investor C Shares	Institutional Shares
Management Fees		0.98%	0.98%	0.98%	0.98%
Distribution (12b-1) and/or Service Fees		0.25%	1.00%	1.00%	none
Other Expenses		0.34%	0.43%	0.36%	0.31%
Acquired Fund Fees and Expenses	[1]	0.01%	0.01%	0.01%	0.01%
Total Annual Fund Operating Expenses	[1]	1.58%	2.42%	2.35%	1.30%
Fee Waivers and/or Expense Reimbursements	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	[2]	1.58%	2.42%	2.35%	1.30%

Example:

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example Investor and Institutional BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor A Shares	677	998	1,340	2,305
Investor B Shares	695	1,105	1,491	2,548
Investor C Shares	338	733	1,255	2,686
Institutional Shares	132	412	713	1,568

You would pay the following expenses if you did not redeem your shares:

Expense Example, No Redemption Investor and Institutional BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO (USD $)	1 Year	3 Years	5 Years	10 Years
Investor B Shares	245	755	1,291	2,548
Investor C Shares	238	733	1,255	2,686

Portfolio Turnover:

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 99% of the average value of its portfolio.

Principal Investment Strategies of the Fund

Under normal market conditions, International Opportunities invests at least 80% of its net assets in equity securities issued by foreign companies of any market capitalization. The Fund may invest up to 40% of its net assets in stocks of issuers in emerging market countries.

The Fund seeks to buy primarily common stock but can also invest in preferred stock and convertible securities. From time to time the Fund may invest in shares of companies through initial public offerings (“IPOs”).

The Fund may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies, or enter into foreign currency transactions, including swaps (collectively, commonly known as derivatives). The Fund typically uses derivatives as a substitute for taking a position in the underlying asset and/or as part of a strategy designed to reduce exposure to other risks, such as currency risk. The Fund may also use derivatives to enhance returns, in which case their use would involve leveraging risk. The Fund may seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts or by using other investment techniques (such as reverse repurchase agreements or dollar rolls). The Fund may also use forward foreign currency exchange contracts (obligations to buy or sell a currency at a set rate in the future).

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in International Opportunities, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.

• Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock.

• Derivatives Risk — The Fund’s use of derivatives may reduce the Fund’s returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives.

• Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets.

• Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions.

• Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include:
  
  — The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight.
  
  — Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.
  
  — The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position.
  
  — The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries.
  
  — Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws.
  
  — Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments.
  
  — The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of several European countries. These events may spread to other countries in Europe, including countries that do not use the Euro. These events may affect the value and liquidity of certain of the Fund’s investments.

• Investment Style Risk — Under certain market conditions, growth investments have performed better during the later stages of economic expansion. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles.

• Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage.

• Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money.

• Mid-Cap Securities Risk — The securities of mid-cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies.

• “New Issues” Risk — “New Issues” are initial public offerings of equity securities of U.S. and non-U.S. issuers. Securities issued in IPOs have no trading history, and information about the companies may be available for very limited periods. In addition, the prices of securities sold in IPOs may be highly volatile or may decline shortly after the initial public offering.

• Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.

Performance Information

The information shows you how International Opportunities’ performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the average annual total returns of each class of the Fund’s shares with that of the MSCI All Country World Index Ex-U.S. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If BlackRock and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s results can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Investor A Shares
ANNUAL TOTAL RETURNS
BlackRock International Opportunities Portfolio
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 28.03% (quarter ended June 30, 2009) and the lowest return for a quarter was –24.50% (quarter ended September 30, 2008).

As of 12/31/12
Average Annual Total Returns

Average Annual Total Returns Investor and Institutional BLACKROCK INTERNATIONAL OPPORTUNITIES PORTFOLIO	1 Year	5 Years	10 Years
Investor A	11.83%	(3.77%)	11.98%
Investor A Return After Taxes on Distributions	11.59%	(3.81%)	11.19%
Investor A Return After Taxes on Distributions and Sale of Shares	8.00%	(3.07%)	10.68%
Investor B	12.50%	(3.88%)	11.89%
Investor C	16.15%	(3.47%)	11.74%
Institutional	18.38%	(2.45%)	12.95%
MSCI All Country World Index Ex-U.S. (Reflects no deduction for fees, expenses or taxes)	16.83%	(2.89%)	9.74%

After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor’s tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Investor B, Investor C and Institutional Shares will vary.

[1] A contingent deferred sales charge ("CDSC") of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at time of purchase as part of an investment of $1,000,000 or more.

[2] The CDSC is 4.50% if shares are redeemed in less than one year. The CDSC for Investor B Shares decreases for redemptions made in subsequent years. After six years there is no CDSC on Investor B Shares. (See the section "Details About the Share Classes - Investor B Shares" in the Fund's prospectus for the complete schedule of CDSCs.)

[3] There is no CDSC on Investor C Shares after one year.

[1] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund's most recent annual report which does not include the Acquired Fund Fees and Expenses.

[2] As described in the "Management of the Funds" section of the Fund's prospectus on pages 62-70, BlackRock has contractually agreed to waive and/or reimburse fees or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) as a percentage of average daily net assets to 1.98% (for Investor A Shares), 2.75% (for Investor B and Investor C Shares) and 1.49% (for Institutional Shares) until February 1, 2014. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.