ACTIVE INTERNATIONAL ALLOCATION PORTFOLIO

ACTIVE INTERNATIONAL ALLOCATION PORTFOLIO

Objective

The Active International Allocation Portfolio (the "Portfolio") seeks long-term capital appreciation by investing primarily, in accordance with country and sector weightings determined by the Adviser, Morgan Stanley Investment Management Inc., in equity securities of non-U.S. issuers which, in the aggregate, replicate broad market indices.

Fees and Expenses

The table below describes the fees and expenses that you may pay if you buy and hold shares of the Portfolio. For purchases of Class A shares, you may qualify for a sales charge discount if the cumulative net asset value ("NAV") of Class A shares of the Portfolio purchased in a single transaction, together with the NAV of all Class A shares of other portfolios of Morgan Stanley Institutional Fund, Inc. (the "Fund") or Class A shares of other Morgan Stanley Multi-Class Funds (as defined in the section of this Prospectus entitled "Shareholder Information—Exchange Privilege") held in Related Accounts (as defined in the section of this Prospectus entitled "Shareholder Information—Sales Charges Applicable to Purchases of Class A Shares"), amounts to $25,000 or more. More information about this combined purchase discount and other discounts is available from your authorized financial intermediary and on page 76 of this Prospectus in the section of entitled "Shareholder Information—Sales Charges Applicable to Purchases of Class A Shares."

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - ACTIVE INTERNATIONAL ALLOCATION PORTFOLIO	CLASS I	CLASS A		Class L	Class C
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	none	5.25%		none	none
Maximum deferred sales charge (load) (as a percentage based on the lesser of the offering price or NAV at redemption)	none	none	[1]	none	1.00%	[2]
Redemption Fee (as a percentage of the amount redeemed on redemptions made within 30 days of purchase)	2.00%	2.00%		2.00%	2.00%

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

Annual Fund Operating Expenses - ACTIVE INTERNATIONAL ALLOCATION PORTFOLIO		CLASS I	CLASS A	Class L	Class C
Advisory Fee		0.65%	0.65%	0.65%	0.65%
Distribution and/or Shareholder Service (12b-1) Fee		none	0.25%	0.75%	1.00%
Other Expenses		0.27%	0.38%	0.47%	2.61%
Total Annual Portfolio Operating Expenses	[1]	0.92%	1.28%	1.87%	4.26%
Fee Waiver and/or Expense Reimbursement	[1]	0.02%	0.03%	0.12%	2.26%
Total Annual Portfolio Operating Expenses After Fee Waiver and/or Expense Reimbursement	[1]	0.90%	1.25%	1.75%	2.00%

Example

The example below is intended to help you compare the cost of investing in the Portfolio with the cost of investing in other mutual funds.

The example assumes that you invest $10,000 in the Portfolio, your investment has a 5% return each year and that the Portfolio's operating expenses remain the same (except that the example incorporates the fee waiver and/or expense reimbursement arrangement for only the first year). Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If You SOLD Your Shares:

Expense Example - ACTIVE INTERNATIONAL ALLOCATION PORTFOLIO - USD ($)	1 Year	3 Years	5 Years	10 Years
CLASS I	92	291	507	1,129
CLASS A	646	907	1,188	1,987
Class L	178	576	1,000	2,181
Class C	303	1,087	1,984	4,286

If You HELD Your Shares:

Expense Example No Redemption - ACTIVE INTERNATIONAL ALLOCATION PORTFOLIO - USD ($)	1 Year	3 Years	5 Years	10 Years
CLASS I	92	291	507	1,129
CLASS A	646	907	1,188	1,987
Class L	178	576	1,000	2,181
Class C	203	1,087	1,984	4,286

Portfolio Turnover

The Portfolio 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 Portfolio shares are held in a taxable account. These costs, which are not reflected in Total Annual Portfolio Operating Expenses or in the Example, affect Portfolio performance. During the most recent fiscal year, the Portfolio's portfolio turnover rate was 30% of the average value of its portfolio.

Principal Investment Strategies

The Adviser seeks to maintain a diversified portfolio of international equity securities based on a top-down approach that emphasizes region, country, sector and industry selection and weighting rather than individual stock selection. The Adviser seeks to capitalize on the significance of region, country, sector and industry selection in international equity portfolio returns by over and underweighting countries and/or sectors based primarily on three factors: (i) valuation; (ii) dynamics/fundamental change; and (iii) market momentum/technicals.

The Adviser's Active International Allocation team analyzes both the global economic environment and the economies of countries throughout the world, focusing mainly on the industrialized countries comprising the MSCI Europe, Australasia, Far East Index (the "MSCI EAFE Index"). The Adviser—on an ongoing basis—establishes the proportion or weighting for each region, country, sector and/or industry (e.g., overweight, underweight or neutral) relative to the MSCI EAFE Index and within each region, country, sector and/or industry, will try to broadly replicate, in the aggregate, the performance of a broad local market index by investing in "baskets" of common stocks and other equity securities. In most cases, the local MSCI index for that country will be one of the broad local market indices. The equity securities in which the Portfolio may invest include common stock, preferred stock, convertible securities, depositary receipts, rights and warrants.

The Portfolio may invest in emerging market or developing countries and, with regard to such investments, may make global, regional and sector allocations to emerging markets, as well as allocations to specific emerging market or developing countries. The Adviser generally considers selling a portfolio holding when it determines that the position no longer satisfies its investment criteria.

The Portfolio may, but it is not required to, use derivative instruments for a variety of purposes, including hedging, risk management, portfolio management or to earn income. The Portfolio's use of derivatives may involve the purchase and sale of derivative instruments such as futures, options, swaps, contracts for difference ("CFDs") and other related instruments and techniques. The Portfolio may utilize foreign currency forward exchange contracts, which are also derivatives, in connection with its investments in foreign securities. Derivative instruments used by the Portfolio will be counted toward the Portfolio's exposure in the types of securities listed above to the extent they have economic characteristics similar to such securities.

Principal Risks

There is no assurance that the Portfolio will achieve its investment objective, and you can lose money investing in this Portfolio. The principal risks of investing in the Portfolio include:

•  Equity Securities. In general, prices of equity securities are more volatile than those of fixed income securities. The prices of equity securities fluctuate, and sometimes widely fluctuate, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic and political conditions. To the extent that the Portfolio invests in convertible securities, and the convertible security's investment value is greater than its conversion value, its price will be likely to increase when interest rates fall and decrease when interest rates rise. If the conversion value exceeds the investment value, the price of the convertible security will tend to fluctuate directly with the price of the underlying security.

•  Foreign and Emerging Market Securities. Investments in foreign markets entail special risks such as currency, political, economic and market risks. There also may be greater market volatility, less reliable financial information, higher transaction and custody costs, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets, which have historically been considered stable, may become more volatile and subject to increased risk due to ongoing developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. The risks of investing in emerging market countries are greater than risks associated with investments in foreign developed countries. In addition, the Portfolio's investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of the investment will fluctuate with the U.S. dollar exchange rates. To the extent hedged by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions could reduce or preclude the opportunity for gain if the value of the currency moves in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Portfolio's securities are not denominated. The use of foreign currency forward exchange contracts involves the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.

•  Liquidity. The Portfolio's investments in illiquid securities may entail greater risk than investments in other types of securities. These securities may be more difficult to sell, particularly in times of market turmoil. Additionally, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Illiquid securities may be more difficult to value. If the Portfolio is forced to sell an illiquid security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss.

•  Derivatives. A derivative instrument often has risks similar to its underlying asset and may have additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates and risks that the transactions may not be liquid. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.

Shares of the Portfolio are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.

Performance Information

The bar chart and table below provide some indication of the risks of investing in the Portfolio by showing changes in the Portfolio's Class I shares' performance from year-to-year and by showing how the Portfolio's average annual returns for the past one, five and 10 year periods and since inception compare with those of a broad measure of market performance, as well as an index that represents a group of similar mutual funds, over time. The performance of the other Classes, which is shown in the table below, will differ because the Classes have different ongoing fees. The Portfolio's returns in the table include the maximum applicable sales charge for Class A and assume you sold your shares at the end of each period (unless otherwise noted). The Portfolio's past performance, before and after taxes, is not necessarily an indication of how the Portfolio will perform in the future. Updated performance information is available online at www.morganstanley.com/im or by calling toll-free (800) 548-7786.

Annual Total Returns—Calendar Years

High Quarter	6/30/09	24.16	%
Low Quarter	9/30/11	–20.43	%

Average Annual Total Returns (for the calendar periods ended December 31, 2015)

Average Annual Returns - ACTIVE INTERNATIONAL ALLOCATION PORTFOLIO		Average Annual Returns, Past One Year	Average Annual Returns, Past Five Years	Average Annual Returns, Past Ten Years	Average Annual Returns, Since Inception		Average Annual Returns, Inception Date
CLASS I		(1.63%)	2.30%	3.07%	5.64%		Jan. 17, 1992
CLASS A		(7.10%)	0.91%	2.23%	4.53%		Jan. 02, 1996
Class L		(2.44%)			7.55%		Jun. 14, 2012
Class C	[1]						Apr. 30, 2015
After Taxes on Distributions | CLASS I		(1.76%)	1.91%	2.49%	4.35%
After Taxes on Distributions and Sale of Fund Shares | CLASS I		(0.65%)	1.84%	2.56%	4.25%
MSCI EAFE Index (reflects no deduction for fees, expenses or taxes)	[2]	(0.81%)	3.60%	3.03%	5.34%	[3]	Jan. 17, 1992
Lipper International Large-Cap Core Funds Index (reflects no deduction for taxes)	[4]	(3.21%)	2.68%	2.51%	6.13%	[3]	Jan. 17, 1992

The after-tax returns shown in the table above are calculated using the historical highest individual federal marginal income tax rates during the period shown and do not reflect the impact of state and local taxes. After-tax returns for the Portfolio's other Classes will vary from Class I shares' returns. Actual after-tax returns depend on the investor's tax situation and may differ from those shown, and after-tax returns are not relevant to investors who hold their Portfolio shares through tax deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns may be higher than before-tax returns due to an assumed benefit from capital losses that would have been realized had Portfolio shares been sold at the end of the relevant periods, as applicable.

[1] Investments that are not subject to any sales charges at the time of purchase are subject to a contingent deferred sales charge ("CDSC") of 1.00% that will be imposed if you sell your shares within 18 months after the last day of the month of purchase, except for certain specific circumstances. See "Shareholder Information-How to Redeem Portfolio Shares" for further information about the CDSC waiver categories.

[2] The Class C CDSC is only applicable if you sell your shares within one year after purchase. See "Shareholder Information-How to Redeem Portfolio Shares" for a complete discussion of the CDSC.

[1] The Adviser has agreed to reduce its advisory fee and/or reimburse the Portfolio so that Total Annual Portfolio Operating Expenses, excluding certain investment related expenses, taxes, interest and other extraordinary expenses (including litigation), will not exceed 0.90% for Class I, 1.25% for Class A, 1.75% for Class L and 2.00% for Class C. The fee waivers and/or expense reimbursements will continue for at least one year or until such time as the Fund's Board of Directors acts to discontinue all or a portion of such waivers and/or reimbursements when it deems such action is appropriate.

[1] Class C shares of the Portfolio had not completed a full calendar year of operations as of December 31, 2015 and therefore Class C shares do not have annualized return information to report.

[2] The MSCI EAFE Index (Europe, Australasia, Far East) is a free float-adjusted market capitalization index that is designed to measure the international equity market performance of developed markets, excluding the United States and Canada. The term "free float" represents the portion of shares outstanding that are deemed to be available for purchase in the public equity markets by investors. The MSCI EAFE Index currently consists of 21 developed market country indices. The performance of the Index is listed in U.S. dollars and assumes reinvestment of net dividends. It is not possible to invest directly in an index.

[3] Since Inception reflects the inception date of Class I.

[4] The Lipper International Large-Cap Core Funds Index is an equally weighted performance index of the largest qualifying funds (based on net assets) in the Lipper International Large-Cap Core Funds classification. There are currently 30 funds represented in this Index. It is not possible to invest directly in an index.