BlackRock International Fund

FEBRUARY 28, 2014

Summary Prospectus

BlackRock International Fund of BlackRock Series, Inc. | Investor, Institutional and Class R Shares

Investor A: MDILX • Investor B: MBILX • Investor C: MCILX • Institutional: MAILX • Class R: BIFRX

Before you invest, you may want to review the Fund’s prospectus, which contains more information about the Fund and its risks. You can find the Fund’s prospectus (including amendments and supplements) and other information about the Fund, including the Fund’s statement of additional information and shareholder report, online at http://www.blackrock.com/prospectus. You can also get this information at no cost by calling (800) 441-7762 or by sending an e-mail request to prospectus.request@blackrock.com, or from your financial professional. The Fund’s prospectus and statement of additional information, both dated February 28, 2014, as amended and supplemented from time to time, are incorporated by reference into (legally made a part of) this Summary Prospectus.

This Summary Prospectus contains information you should know before investing, including information about risks. Please read it before you invest and keep it for future reference.

The Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this Summary Prospectus. Any representation to the contrary is a criminal offense.

Not FDIC Insured • May Lose Value • No Bank Guarantee

Summary Prospectus

Key Facts About BlackRock International Fund of BlackRock Series, Inc.

Investment Objective

The investment objective of BlackRock International Fund (“International Fund” or the “Fund”), a series of BlackRock Series, Inc. (the “Corporation”), is to seek long-term capital growth through investments primarily in a diversified portfolio of equity securities of companies located outside the United States.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. 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”) and its affiliates. More information about these and other discounts is available from your financial professional or your selected securities dealer, broker, investment adviser, service provider or industry professional (including BlackRock, The PNC Financial Services Group, Inc. and their respective affiliates) (each a “Financial Intermediary”) and in the “Details About the Share Classes” section on page 36 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-60 of Part II of the Fund’s Statement of Additional Information.

Shareholder Fees (fees paid directly from your investment)		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)⁴		Investor A Shares		Investor B Shares		Investor C Shares		Institutional Shares		Class R Shares
Management Fee⁴		0.73%		0.73%		0.73%		0.73%		0.73%
Distribution and/or Service (12b-1) Fees		0.25%		1.00%		1.00%		None		0.50%
Other Expenses		0.58%		1.31%		0.76%		0.49%		0.62%
Administration Fees	0.25%		0.25%		0.25%		0.25%		0.25%
Miscellaneous Other Expenses	0.33%		1.06%		0.51%		0.24%		0.37%
Total Annual Fund Operating Expenses		1.56%		3.04%		2.49%		1.22%		1.85%
Fee Waivers and/or Expense Reimbursements⁵		(0.18)%		(0.60)%		(0.07)%		(0.22)%		(0.15)%
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements⁵		1.38%		2.44%		2.42%		1.00%		1.70%

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.
⁴	The fees and expenses shown in the table and the example that follows include both the expenses of International Fund and International Fund’s share of the allocated expenses of BlackRock Master International Portfolio (“Master International Portfolio”). Management fees are paid by Master International Portfolio.
⁵	As described in the “Management of the Funds” section of the Fund’s prospectus on pages 51-57, BlackRock has contractually agreed to waive and/or reimburse fees and/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 1.38% (for Investor A Shares), 2.44% (for Investor B Shares), 2.42% (for Investor C Shares), 1.00% (for Institutional Shares) and 1.70% (for Class R Shares) until March 1, 2015. The agreement may be terminated upon 90 days’ notice by a majority of the non-interested directors of the Corporation or by a vote of a majority of the outstanding voting securities of the Fund.

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:

	1 Year	3 Years	5 Years	10 Years
Investor A Shares	$658	$ 975	$1,314	$2,270
Investor B Shares	$697	$1,233	$1,744	$2,964
Investor C Shares	$345	$ 769	$1,319	$2,821
Institutional Shares	$102	$ 365	$ 649	$1,458
Class R Shares	$173	$ 567	$ 987	$2,157

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

	1 Year	3 Years	5 Years	10 Years
Investor B Shares	$247	$883	$1,544	$2,964
Investor C Shares	$245	$769	$1,319	$2,821

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 rate 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 128% of the average value of its portfolio.

Principal Investment Strategies of the Fund

International Fund is a “feeder” fund that invests all of its assets in Master International Portfolio, a series of BlackRock Master LLC (the “Master LLC”), which has the same investment objective and strategies as the Fund. All investments are made at the level of Master International Portfolio. This structure is sometimes called a “master/feeder” structure. The Fund’s investment results will correspond directly to the investment results of Master International Portfolio. For simplicity, the sections of this prospectus relating to International Fund use the term “Fund” or the name of the Fund to include the underlying Master International Portfolio.

The Fund invests primarily in stocks of companies located outside the United States. The Fund may purchase common stock, preferred stock, convertible securities and other instruments.

The Fund 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 may invest in securities issued by companies of all sizes but will focus mainly on medium and large capitalization companies. Companies will be located in developed countries of Europe and the Far East, and in countries with emerging capital markets anywhere in the world. 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).

Fund management selects companies that it believes are undervalued or have good prospects for earnings growth. The Fund chooses investments predominantly using a “bottom up” investment style using a global sector-based investment process. The Fund’s allocations to particular countries are based on Fund management’s evaluation of individual companies.

Under normal circumstances, the Fund will allocate a substantial amount (approximately 40% or more — unless market conditions are not deemed favorable by Fund management, in which case the Fund would invest at least 30%) of its total assets in securities (i) of foreign government issuers, (ii) of issuers organized or located outside the United States, (iii) of issuers which primarily trade in a market located outside the United States, or (iv) of issuers doing a substantial amount of business outside the United States, which the Fund considers to be companies that derive at least 50% of their revenue or profits from business outside the United States or have at least 50% of their sales or assets outside the United States. The Fund will allocate its assets among various regions and countries, including the

United States (but in no less than three different countries). For temporary defensive purposes the Fund may deviate very substantially from the allocation described above.

Fund management may, when consistent with the Fund’s investment objective, buy or sell options or futures on a security or an index of securities, or enter into interest rate or foreign currency transactions, including swaps (collectively, commonly known as derivatives).

Principal Risks of Investing in the Fund

Risk is inherent in all investing. The value of your investment in International Fund, 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.

■	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. 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. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. 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. Valuation may be more difficult in times of market turmoil since many investors and market makers may be reluctant to purchase complex instruments or quote prices for them. Derivatives also may expose the Fund to greater risk and increase its costs. Certain transactions in derivatives involve substantial leverage risk and may expose the Fund to potential losses that exceed the amount originally invested by the Fund. 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 an equity security 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. 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.
■	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.

Performance Information

The information shows you how International 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 MSCI All Country World Index Ex-U.S. Class R Shares commenced operations on August 15, 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 applicable distribution and service (12b-1) fees. 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 performance, including its current net asset value, can be obtained by visiting www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.

Investor A Shares

ANNUAL TOTAL RETURNS¹
International Fund
As of 12/31

During the ten-year period shown in the bar chart, the highest return for a quarter was 27.62% (quarter ended June 30, 2009) and the lowest return for a quarter was –22.50% (quarter ended September 30, 2008).

As of 12/31/13 Average Annual Total Returns	1 Year¹	5 Years¹	10 Years¹
BlackRock International Fund — Investor A
Return Before Taxes	15.80%	12.52%	5.75%
Return After Taxes on Distributions	15.56%	12.40%	5.66%
Return After Taxes on Distributions and Sale of Shares	9.46%	10.05%	4.68%
BlackRock International Fund — Investor B

As of 12/31/13 Average Annual Total Returns	1 Year¹	5 Years¹	10 Years¹
Return Before Taxes	16.39%	12.24%	5.48%
BlackRock International Fund — Investor C
Return Before Taxes	19.94%	12.78%	5.46%
BlackRock International Fund — Institutional
Return Before Taxes	22.59%	14.14%	6.65%
BlackRock International Fund — Class R
Return Before Taxes	21.73%	13.47%	6.07%
MSCI All Country World Index Ex-U.S. (Reflects no deduction for fees, expenses or taxes)	15.29%	12.81%	7.57%

¹	For the fiscal year ended October 31, 2013, a portion of the Fund’s return for each share class consisted of a payment from an affiliate to compensate for foregone securities lending revenue.

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.

Investment Manager

International Fund’s investment manager is BlackRock Advisors, LLC (previously defined as “BlackRock”). The Fund’s sub-adviser is BlackRock International Limited (the “Sub-Adviser”). Where applicable, “BlackRock” refers also to the Sub-Adviser.

Portfolio Managers

Name	Portfolio Manager of the Fund Since	Title
James Bristow, CFA	2007	Managing Director of BlackRock, Inc.
Gareth Williams, CFA	2011	Director of BlackRock, Inc.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of International Fund each day the New York Stock Exchange is open. To purchase or sell shares you should contact your Financial Intermediary, or, if you hold your shares through the Fund, you should contact the Fund by phone at (800) 441-7762, by mail (c/o BlackRock Funds, P.O. Box 9819, Providence, Rhode Island 02940-8019), or by the Internet at www.blackrock.com/funds. The Fund’s initial and subsequent investment minimums generally are as follows, although the Fund may reduce or waive the minimums in some cases:

	Investor A and Investor C Shares	Investor B Shares	Institutional Shares	Class R Shares
Minimum Initial Investment	$1,000 for all accounts except: • $250 for certain fee-based programs. • $100 for certain employer-sponsored retirement plans. • $50, if establishing an Automatic Investment Plan.	Available only through exchanges and dividend reinvestments by current holders and for purchase by certain employer-sponsored retirement plans.	$2 million for institutions and individuals. Institutional Shares are available to clients of registered investment advisers who have $250,000 invested in the Fund.	$100 for all accounts.

	Investor A and Investor C Shares	Investor B Shares	Institutional Shares	Class R Shares
Minimum Additional Investment	$50 for all accounts (with the exception of certain employer-sponsored retirement plans which may have a lower minimum).	N/A	No subsequent minimum.	No subsequent minimum.

Tax Information

International Fund’s dividends and distributions may be subject to Federal income taxes and may be taxed as ordinary income or capital gains, unless you are a tax-exempt investor or are investing through a retirement plan, in which case you may be subject to Federal income tax upon withdrawal from such tax-deferred arrangements.

Payments to Broker/Dealers and Other Financial Intermediaries

If you purchase shares of International Fund through a Financial Intermediary, the Fund and BlackRock Investments, LLC, the Fund’s distributor, or its affiliates may pay the Financial Intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the Financial Intermediary and your individual financial professional to recommend the Fund over another investment. Ask your individual financial professional or visit your Financial Intermediary’s website for more information.

INVESTMENT COMPANY ACT FILE # 811-08797

SPRO-IF-0214