November 2, 2006

Supplement

SUPPLEMENT DATED NOVEMBER 2, 2006 TO THE STATEMENT OF ADDITIONAL INFORMATION OF
MORGAN STANLEY DEVELOPING GROWTH SECURITIES TRUST
Dated January 27, 2006 

The information in the Fund's Statement of Additional Information in the section titled ‘‘II. Description of the Fund and Its Investments and Risks – C. Fund Policies/Investment Restrictions’’ is hereby deleted and replaced with the following: 

C.    Fund Policies/Investment Restrictions 

The investment objective, policies and restrictions listed below have been adopted by the Fund as fundamental policies. Under the Investment Company Act, a fundamental policy may not be changed without the vote of a majority of the outstanding voting securities of the Fund. The Investment Company Act defines a majority as the lesser of (a) 67% or more of the shares present at a meeting of shareholders, if the holders of 50% of the outstanding shares of the Fund are present or represented by proxy; or (b) more than 50% of the outstanding shares of the Fund. For purposes of the following restrictions: (i) all percentage limitations apply immediately after a purchase or initial investment (unless otherwise noted); and (ii) any subsequent change in any applicable percentage resulting from market fluctuations or other changes in total or net assets does not require elimination of any security from the portfolio, except in the case of borrowing and investments in illiquid securities. 

The Fund will: 

1. 

Seek long-term capital growth. 

The Fund may not: 

1. 

Invest in a manner inconsistent with its classification as a ‘‘diversified company’’ as provided by (i) the Investment Company Act, as amended from time to time, (ii) the rules and regulations promulgated by the SEC under the Investment Company Act, as amended from time to time, or (iii) an exemption or other relief applicable to the Fund from the provisions of the Investment Company Act, as amended from time to time. 

2. 

Concentrate its investments in any particular industry, but if deemed appropriate for attainment of its investment objective, up to 25% of its total assets (valued at the time of investment) may be invested in any one industry classification used by the Fund for investment purposes. This restriction does not apply to obligations issued or guaranteed by the U.S. government or its agencies or instrumentalities. 

3. 

Borrow money, except the Fund may borrow money to the extent permitted by (i) the Investment Company Act, as amended from time to time, (ii) the rules and regulations promulgated by the SEC under the Investment Company Act, as amended from time to time, or (iii) an exemption or other relief applicable to the Fund from the provisions of the Investment Company Act, as amended from time to time. 

4. 

Purchase or sell real estate or interests therein, although the Fund may purchase securities of issuers which engage in real estate operations and securities which are secured by real estate or interests therein. 

5. 

Purchase or sell physical commodities unless acquired as a result of ownership of securities or other instruments; provided that this restriction shall not prohibit the Fund from purchasing or selling options, futures contracts and related options thereon, forward contracts, swaps, caps, floors, collars and any other financial instruments or from investing in securities or other instruments backed by physical commodities or as otherwise permitted by (i) the Investment Company Act, as amended from time to time, (ii) the rules and regulations promulgated by the SEC under the Investment Company Act, as amended from time to time, or (iii) an exemption or other relief applicable to the Fund from the provisions of the Investment Company Act, as amended from time to time. 

6. 

Issue senior securities, except the Fund may issue senior securities to the extent permitted by (i) the Investment Company Act, as amended from time to time, (ii) the rules and regulations promulgated by the SEC under the Investment Company Act, as amended from time to time, or (iii) an exemption or other relief applicable to the Fund from the provisions of the Investment Company Act, as amended from time to time. 

7. 

Make loans of money or property to any person except (a) to the extent that securities or interests in which the Fund may invest are considered to be loans, (b) through the loan of portfolio securities, (c) by engaging in repurchase agreements or (d) as may otherwise be permitted by (i) the Investment Company Act, as amended from time to time, (ii) the rules and regulations promulgated by the SEC under the Investment Company Act, as amended from time to time, or (iii) an exemption or other relief applicable to the Fund from the provision of the Investment Company Act, as amended from time to time. 

8. 

Engage in the underwriting of securities, except insofar as the Fund may be deemed an underwriter under the Securities Act in disposing of a portfolio security. 

In addition, as a non-fundamental policy, which may be changed with Board approval and without shareholder vote, the Fund will not: 

1. 

Make short sales of securities, except short sales against the box. 

2. 

Invest its assets in the securities of any investment company except as may be permitted by (i) the Investment Company Act, as amended from time to time; (ii) the rules and regulations promulgated by the SEC under the Investment Company Act, as amended from time to time; or (iii) an exemption or other relief applicable to the Fund from the provisions of the Investment Company Act, as amended from time to time. 

3. 

Write, purchase or sell puts, calls or combinations thereof. 

4. 

Invest in other investment companies in reliance on Sections 12(d)(1)(F), 12(d)(1)(G) or 12(d)(1)(J) of the Investment Company Act. 

The Fund has an operating policy, which may be changed by the Fund's Board of Trustees, not to borrow except from a bank for temporary emergency purposes in amounts not exceeding 5% (taken at the lower of cost or current value) of its total assets (not including the amount borrowed). 

Notwithstanding any other investment policy or restriction, the Fund may seek to achieve its investment objective by investing all or substantially all of its assets in another investment company having substantially the same investment objective and policies as the Fund. 

PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE.