UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   FORM N-CSR

                   CERTIFIED SHAREHOLDER REPORT OF REGISTERED
                         MANAGEMENT INVESTMENT COMPANIES

Investment Company Act file number: 811-03639

Morgan Stanley Developing Growth Securities Trust
               (Exact name of registrant as specified in charter)

1221 Avenue of the Americas, New York, New York 10020
       (Address of principal executive offices)                       (Zip code)

Ronald E. Robison
1221 Avenue of the Americas, New York, New York 10020
                     (Name and address of agent for service)

Registrant's telephone number, including area code: 212-762-4000

Date of fiscal year end: September 30, 2006

Date of reporting period: March 31, 2006


Item 1 - Report to Shareholders

Welcome, Shareholder:

In this report, you'll learn about how your investment in Developing Growth Securities Trust performed during the semiannual period. We will provide an overview of the market conditions, and discuss some of the factors that affected performance during the reporting period. In addition, this report includes the Fund's financial statements and a list of Fund investments.

This material must be preceded or accompanied by a prospectus for the fund being offered.

Market forecasts provided in this report may not necessarily come to pass. There is no assurance that the Fund will achieve its investment objective. The Fund is subject to market risk, which is the possibility that market values of securities owned by the Fund will decline and, therefore, the value of the Fund’s shares may be less than what you paid for them. Accordingly, you can lose money investing in this Fund. Please see the prospectus for more complete information on investment risks.

	Fund Report
	For the six months ended March 31, 2006

Total Return for the 6 Months Ended March 31, 2006

Class A						Class B						Class C						Class D						Russell Midcap® Growth Index1						Lipper Mid-Cap Growth Funds Index2
15.69%							15.24	%					15.28	%					15.77	%					11.32	%					12.88	%

The performance of the Fund’s four share classes varies because each has different expenses. The Fund’s total returns assume the reinvestment of all distributions but do not reflect the deduction of any applicable sales charges. Such costs would lower performance. See Performance Summary for standardized performance and benchmark information.

Market Conditions

The reporting period began in the midst of a market downturn caused by the Gulf Coast hurricanes. Record high energy prices and a shortfall in consumer spending trends heightened concerns that the economy could be headed for recession. However, sentiment recovered in October on the back of more positive economic news, leading to a very strong rally in November. The stock market began 2006 on an upbeat note, despite disappointing news on the economic growth and corporate earnings fronts. The Federal Open Market Committee continued to raise the federal funds rate (with four increases during the six-month period) and, as of the close of the period, left the door open for future increases. Investors continued to view inflation as contained and considered the slow down in fourth quarter gross domestic product to be temporary, attributing the below expectation data to hurricane-related losses.

In this environment, mid-capitalization stocks continued to perform well both on an absolute and relative basis. Although small-cap stocks led, mid-caps outpaced large-caps during the period. Within the mid-cap universe, growth stocks outperformed value stocks, as the rising stock market and moderately strong economy bolstered investors’ confidence in companies with faster growth prospects.

Performance Analysis

Morgan Stanley Developing Growth Securities Trust outperformed the Russell Midcap^® Growth Index and the Lipper Mid-Cap Growth Funds Index for the six months ended March 31, 2006, assuming no deduction of applicable sales charges.

Stock selection drove the Fund’s outperformance relative to the Russell Midcap Growth Index, more than offsetting the modestly negative influence of sector allocation. The top contributing sectors to relative results were autos and transportation, financial services, and energy. A comparative overweight in the autos and transportation sector added to results, as did our stock picks in the miscellaneous transportation and the air transportation industries. Stock selection in the financial services sector had a favorable impact on relative performance, primarily in diversified financial services and investment management companies. Within energy, exposure to the crude oil producers industry and an overall sector underweight enhanced gains.

2

In contrast, the materials and processing and producer durables sectors slowed the Fund’s pace relative to the Index. An underweight in the materials and processing sector combined with a lack of exposure to copper and steel companies turned out to be disadvantageous during the period. Within the producer durables sector, stock picking within the office furniture and business equipment industry was detrimental. Additionally, an avoidance of the identification control industry detracted from relative results.

At the period’s close, consumer discretionary represented the Fund’s largest sector weight, followed by financial services and health care. The Fund’s consumer discretionary exposure is overweighted relative to the Russell Midcap Growth Index, while health care and financial services are underweighted versus the Index.

There is no guarantee that any sectors mentioned will continue to perform as discussed herein or that securities in such sectors will be held by the Fund in the future.

Investment Strategy

The Fund will normally invest at least 65 percent of its assets in common stocks (including depositary receipts) and other equity securities. The Fund’s ‘‘Investment Adviser,’’ Morgan Stanley Investment Advisors Inc., follows a flexible investment program in seeking to achieve the Fund’s investment objective. The Investment Adviser focuses on companies it believes have consistent or rising earnings growth records, potential for strong free cash flow and compelling business strategies. In this regard, the Investment Adviser studies company developments, including business strategy and financial results. Valuation is viewed in the context of prospects for sustainable earnings and cash flow growth. The Investment Adviser generally considers selling a portfolio holding when it determines that the holding no longer satisfies its investment criteria.

For More Information About
Portfolio Holdings

Each Morgan Stanley fund provides a complete schedule of portfolio holdings in its semiannual and annual reports by filing the schedule electronically with the Securities and Exchange Commission (SEC). The semiannual reports are filed on Form N-CSRS and the annual reports are filed on Form N-CSR. Morgan Stanley also delivers the semiannual and annual reports to fund shareholders and makes these reports available on its public Web site, www.morganstanley.com. Each Morgan Stanley fund also files a complete schedule of portfolio holdings with the SEC for the fund’s first and third fiscal quarters on Form N-Q. Morgan Stanley does not deliver the reports for the first and third fiscal quarters to shareholders, nor are the reports posted to the Morgan Stanley publi web site. You may, however,

3

TOP 10 HOLDINGS
Ultra Petroleum Corp. (Canada)					5.9	%
Corporate Executive Board Co. (The)					4.1
NII Holdings, Inc. (Class B)					3.9
Monster Worldwide, Inc.					3.1
AutoZone, Inc.					3.0
Station Casinos, Inc.					3.0
Expeditors International of Washington, Inc.					2.8
C.H. Robinson Worldwide, Inc.					2.8
Getty Images, Inc.					2.7
Stericycle, Inc.					2.4

TOP FIVE INDUSTRIES
Oil & Gas Production					7.7	%
Miscellaneous Commercial Services					6.3
Other Consumer Services					5.6
Air Freight/Couriers					5.6
Restaurants					5.0

Data as of March 31, 2006. Subject to change daily. All percentages for top 10 holdings and top five industries are as a percentage of net assets. These data are provided for informational purposes only and should not be deemed a recommendation to buy or sell the securities mentioned. Morgan Stanley is a full-service securities firm engaged in securities trading and brokerage activities, investment banking, research and analysis, financing and financial advisory services.

obtain the Form N-Q filings (as well as the Form N-CSR and N-CSRS filings) by accessing the SEC’s Web site, http://www.sec.gov. You may also review and copy them at the SEC’s Public Reference Room in Washington, DC. Information on the operation of the SEC’s Public Reference Room may be obtained by calling the SEC at (800) SEC-0330. You can also request copies of these materials, upon payment of a duplicating fee, by electronic request at the SEC’s e-mail address (publicinfo@sec.gov) or by writing the Public Reference section of the SEC, Washington, DC 20549-0102.

Proxy Voting Policy and Procedures and Proxy Voting Record

You may obtain a copy of the Fund’s Proxy Voting Policy and Procedures without charge, upon request, by calling toll free (800) 869-NEWS or by visiting the Mutual Fund Center on our Web site at www.morganstanley.com. It is also available on the Securities and Exchange Commission’s Web site at http://www.sec.gov.

You may obtain information regarding how the Fund voted proxies relating to portfolio securities during the most recent twelve-month period ended June 30 without charge by visiting the Mutual Fund Center on our Web site at www.morganstanley.com. This information is also available on the
Securities and Exchange Commission’s Web site at http://www.sec.gov.

4

Householding Notice

To reduce printing and mailing costs, the Fund attempts to eliminate duplicate mailings to the same address. The Fund delivers a single copy of certain shareholder documents, including shareholder reports, prospectuses and proxy materials, to investors with the same last name who reside at the same address. Your participation in this program will continue for an unlimited period of time unless you instruct us otherwise. You can request multiple copies of these documents by calling (800) 350-6414, 8:00 a.m. to 8:00 p.m., ET. Once our Customer Service Center has received your instructions, we will begin sending individual copies for each account within 30 days.

5

	Performance Summary

Average Annual Total Returns — Period Ended March 31, 2006

						Class A Shares* (since 07/28/97)						Class B Shares** (since 04/29/83)						Class C Shares† (since 07/28/97)						Class D Shares†† (since 07/28/97)
Symbol						DGRAX						DGRBX						DGRCX						DGRDX
1 Year							32.77%	3					31.76%	3					31.80%	3					33.08%	3
							25.80	4					26.76	4					30.80	4					—
5 Years							9.66	3					8.81	3					8.84	3					9.90	3
							8.48	4					8.52	4					8.84	4					—
10 Years							—						8.54	3					—						—
							—						8.54	4					—						—
Since Inception							8.81	3					8.78	3					8.00	3					9.04	3
							8.13	4					8.78	4					8.00	4					—

Performance data quoted represents past performance, which is no guarantee of future results and current performance may be lower or higher than the figures shown. For most recent month-end performance figures, please visit www.morganstanley.com or speak with your Financial Advisor. Investment returns and principal value will fluctuate and fund shares, when redeemed, may be worth more or less than their original cost. The table does not reflect the deduction of taxes that a shareholder would pay on fund distributions or the redemption of fund shares. Performance for Class A, Class B, Class C, and Class D shares will vary due to differences in sales charges and expenses.

* The maximum front-end sales charge for Class A is 5.25%.

** The maximum contingent deferred sales charge (CDSC) for Class B is 5.0%. The CDSC declines to 0% after six years.

† The maximum contingent deferred sales charge for Class C is 1.0% for shares redeemed within one year of purchase.

†† Class D has no sales charge.

(1) The Russell Midcap^® Growth Index measures the performance of those Russell Midcap^® Index companies with higher price-to-book ratios and higher forecasted growth values. The stocks are also members of the Russell 1000^® Growth Index. Indexes are unmanaged and their returns do not include any sales charges or fees. Such costs would lower performance. It is not possible to invest directly in an index.

(2) The Lipper Mid-Cap Growth Funds Index is an equally weighted performance index of the largest qualifying funds (based on net assets) in the Lipper Mid-Cap Growth Funds classification. The Index, which is adjusted for capital gains distributions and income dividends, is unmanaged and should not be considered an investment. There are currently 30 funds represented in this Index.

(3) Figure shown assumes reinvestment of all distributions and does not reflect the deduction of any sales charges.

(4) Figure shown assumes reinvestment of all distributions and the deduction of the maximum applicable sales charge. See the Fund's current prospectus for complete details on fees and sales charges.

6

	Expense Example

As a shareholder of the Fund, you incur two types of costs: (1) transaction costs, including sales charges (loads) on purchase payments and redemption fees; and (2) ongoing costs, including advisory fees; distribution and service (12b-1) fees; and other Fund expenses. This example is intended to help you understand your ongoing costs (in dollars) of investing in the Fund and to compare these costs with the ongoing costs of investing in other mutual funds.

The example is based on an investment of $1,000 invested at the beginning of the period and held for the entire period 10/01/05 – 03/31/06.

Actual Expenses

The first line of the table below provides information about actual account values and actual expenses. You may use the information in this line, together with the amount you invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the result by the number in the first line under the heading entitled ‘‘Expenses Paid During Period’’ to estimate the expenses you paid on your account during this period.

Hypothetical Example for Comparison Purposes

The second line of the table below provides information about hypothetical expenses based on the Fund’s actual expense ratio and an assumed rate of return of 5% per year before expenses, which is not the Fund’s actual return. The hypothetical account values and expenses may not be used to estimate the actual ending account balance or expenses you paid for the period. You may use this information to compare the ongoing cost of investing in the Fund and other funds. To do so, compare this 5% hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of the other funds.

Please note that the expenses shown in the table are meant to highlight your ongoing costs only and do not reflect any transactional costs, such as sales charges (loads) and redemption fees. Therefore, the second line of the table is useful in comparing ongoing costs, and will not help you determine the relative total cost of owning different funds. In addition, if these transactional costs were included, your costs would have been higher.

				Beginning Account Value				Ending Account Value				Expenses Paid During Period*
				10/01/05				03/31/06				10/01/05 – 03/31/06
Class A
Actual (15.69% return)				$	1,000.00			$	1,156.90			$	5.65
Hypothetical (5% annual return before expenses)				$	1,000.00			$	1,019.70			$	5.29
Class B
Actual (15.24% return)				$	1,000.00			$	1,152.40			$	9.77
Hypothetical (5% annual return before expenses)				$	1,000.00			$	1,015.86			$	9.15
Class C
Actual (15.28% return)				$	1,000.00			$	1,152.80			$	9.71
Hypothetical (5% annual return before expenses)				$	1,000.00			$	1,015.91			$	9.10
Class D
Actual (15.77% return)				$	1,000.00			$	1,157.70			$	4.41
Hypothetical (5% annual return before expenses)				$	1,000.00			$	1,020.84			$	4.13

* Expenses are equal to the Fund's annualized expense ratio of 1.05%, 1.82%, 1.81% and 0.82% for Class A, Class B, Class C and Class D shares, respectively, multiplied by the average account value over the period, multiplied by 182/365 (to reflect the one-half year period).

7

Morgan Stanley Developing Growth Securities Trust

Portfolio of Investments March 31, 2006 (unaudited)

NUMBER OF SHARES								VALUE
				Common Stocks (99.9%)
				Advertising/Marketing Services (4.2%)
	186,755			Getty Images, Inc.*				$	13,984,214
	151,119			Lamar Advertising Co. (Class A)*					7,951,882
									21,936,096
				Air Freight/Couriers (5.6%)
	298,240			C.H. Robinson Worldwide, Inc.					14,640,602
	171,739			Expeditors International of Washington, Inc.					14,836,532
									29,477,134
				Apparel/Footwear Retail (3.0%)
	116,500			Abercrombie & Fitch Co. (Class A)					6,791,950
	302,900			American Eagle Outfitters, Inc.*					9,044,594
									15,836,544
				Biotechnology (3.0%)
	190,984			Gen-Probe Inc.*					10,527,038
	91,973			Techne Corp.*					5,531,256
									16,058,294
				Casino/Gaming (4.4%)
	214,370			International Game Technology					7,550,111
	196,868			Station Casinos, Inc.					15,625,413
									23,175,524
				Construction Materials (1.5%)
	136,300			Florida Rock Industries, Inc.					7,662,786
				Data Processing Services (2.0%)
	102,500			CheckFree Corp.*					5,176,250
	97,900			Global Payments Inc.					5,189,679
									10,365,929
				Electronic Production Equipment (1.1%)
	186,426			Tessera Technologies, Inc.*					5,980,546
				Financial Conglomerates (2.1%)
	202,764			Brookfield Asset Mangement Inc. (Class A) (Canada)					11,164,186
				Gas Distributors (0.9%)
	67,602			Questar Corp.					4,735,520
				Home Building (2.8%)
	207,564			Desarrolladora Homex S.A. de C.V. (ADR) (Mexico)*				$	7,333,236
	10,067			NVR, Inc.*					7,439,010
									14,772,246
				Hotels/Resorts/Cruiselines (1.3%)
	152,360			Choice Hotels International, Inc.					6,975,041
				Insurance Brokers/Services (2.0%)
	165,384			Brown & Brown, Inc.					5,490,749
	111,882			ChoicePoint, Inc.*					5,006,720
									10,497,469
				Internet Retail (1.4%)
	200,300			Amazon.com, Inc.*					7,312,953
				Internet Software/Services (2.5%)
	192,100			Akamai Technologies, Inc.*					6,318,169
	279,568			Netease.com Inc. (ADR) (Cayman Islands)*					6,860,599
									13,178,768
				Investment Banks/Brokers (3.1%)
	23,978			Chicago Mercantile Exchange Holdings, Inc.					10,730,155
	259,898			TD AmeriTrade Holding Corp.					5,424,071
									16,154,226
				Investment Managers (3.2%)
	301,788			Calamos Asset Management Inc. (Class A)					11,286,871
	233,000			Janus Capital Group, Inc.					5,398,610
									16,685,481
				Medical Specialties (2.0%)
	288,005			Dade Behring Holdings, Inc.					10,284,659
				Medical/Nursing Services (1.0%)
	86,663			DaVita, Inc.*					5,217,979
				Miscellaneous Commercial Services (6.3%)
	213,717			Corporate Executive Board Co. (The)					21,564,045
	291,206			Iron Mountain Inc.*					11,863,732
									33,427,777
				Miscellaneous     Manufacturing (2.1%)
	272,652			Pentair, Inc.					11,110,569

See Notes to Financial Statements

8

Morgan Stanley Developing Growth Securities Trust

Portfolio of Investments March 31, 2006 (unaudited) continued

NUMBER OF SHARES								VALUE
				Oil & Gas Production (7.7%)
	289,720			Southwestern Energy Co.*				$	9,326,087
	501,021			Ultra Petroleum Corp. (Canada)*					31,218,619
									40,544,706
				Other Consumer Services (5.6%)
	194,900			Apollo Group, Inc. (Class A)*					10,234,199
	307,558			Expedia, Inc.*					6,234,201
	123,709			ITT Educational Services, Inc.*					7,923,561
	104,881			Weight Watchers International, Inc.					5,390,883
									29,782,844
				Packaged Software (3.2%)
	312,235			Red Hat, Inc.*					8,736,335
	230,722			Salesforce.com Inc.*					8,382,130
									17,118,465
				Personnel Services (3.1%)
	329,245			Monster Worldwide, Inc.*					16,416,156
				Property – Casualty Insurers (1.0%)
	9,159			White Mountains Insurance Group, Ltd. (Bermuda)					5,445,026
				Real Estate Development (2.5%)
	99,051			CB Richard Ellis Group, Inc. (Class A)*					7,993,416
	82,172			St. Joe Co. (The)					5,163,688
									13,157,104
				Recreational Products (2.2%)
	842,409			Activision, Inc.*					11,616,820
				Restaurants (5.0%)
	137,504			Cheesecake Factory, Inc. (The)*					5,149,525
	111,800			Outback Steakhouse, Inc.					4,919,200
	136,552			P.F. Chang's China Bistro, Inc.*					6,730,648
	158,051			Wendy's International, Inc.					9,808,645
									26,608,018
				Semiconductors (0.9%)
	85,949			Marvell Technology Group, Ltd. (Bermuda)*					4,649,841
				Services to the Health Industry (2.4%)
	186,987			Stericycle, Inc.*				$	12,644,061
				Specialty Stores (3.0%)
	160,740			AutoZone, Inc.*					16,024,171
				Specialty     Telecommunications (2.3%)
	421,792			Crown Castle International Corp.*					11,957,803
				Tobacco (1.6%)
	173,613			Loews Corp. – Carolina Group					8,206,687
				Wireless     Telecommunications (3.9%)
	346,760			NII Holdings, Inc. (Class B)*					20,448,437
				Total Common Stocks (Cost $405,826,926)					526,629,866

PRINCIPAL AMOUNT IN THOUSANDS
				Short-Term Investment (0.3%)
				Repurchase Agreement
$	1,535			Joint repurchase agreement account 4.785% due 04/03/06 (dated 3/31/06; proceeds $1,535,612) (a) (Cost $1,535,000)					1,535,000

Total Investments (Cost $407,361,926) (b)					100.2	%			528,164,866
Liabilities in Excess of Other Assets					(0.2	)			(793,084	)
Net Assets					100.0	%		$	527,371,782

ADR American Depositary Receipt.

* Non-income producing security.

(a) Collateralized by federal agency and U.S. Treasury obligations.

(b) The aggregate cost for federal income tax purposes approximates the aggregate cost for book purposes. The aggregate gross unrealized appreciation is $128,512,225 and the aggregate gross unrealized depreciation is $7,709,285, resulting in net unrealized appreciation of $120,802,940.

See Notes to Financial Statements

9

Morgan Stanley Developing Growth Securities Trust

Summary of Investments March 31, 2006 (unaudited)

INDUSTRY				VALUE				PERCENT OF NET ASSETS
Oil & Gas Production				$	40,544,706				7.7	%
Miscellaneous Commercial Services					33,427,777				6.3
Other Consumer Services					29,782,844				5.6
Air Freight/Couriers					29,477,134				5.6
Restaurants					26,608,018				5.0
Casino/Gaming					23,175,524				4.4
Advertising/Marketing Services					21,936,096				4.2
Wireless Telecommunications					20,448,437				3.9
Packaged Software					17,118,465				3.2
Investment Managers					16,685,481				3.2
Personnel Services					16,416,156				3.1
Investment Banks/Brokers					16,154,226				3.1
Biotechnology					16,058,294				3.0
Specialty Stores					16,024,171				3.0
Apparel/Footwear Retail					15,836,544				3.0
Home Building					14,772,246				2.8
Internet Software/Services					13,178,768				2.5
Real Estate Development					13,157,104				2.5
Services to the Health Industry					12,644,061				2.4
Specialty Telecommunications				$	11,957,803				2.3	%
Recreational Products					11,616,820				2.2
Financial Conglomerates					11,164,186				2.1
Miscellaneous Manufacturing					11,110,569				2.1
Insurance Brokers/Services					10,497,469				2.0
Data Processing Services					10,365,929				2.0
Medical Specialties					10,284,659				2.0
Tobacco					8,206,687				1.6
Construction Materials					7,662,786				1.5
Internet Retail					7,312,953				1.4
Hotels/Resorts/Cruiselines					6,975,041				1.3
Electronic Production Equipment					5,980,546				1.1
Property – Casualty Insurers					5,445,026				1.0
Medical/Nursing Services					5,217,979				1.0
Gas Distributors					4,735,520				0.9
Semiconductors					4,649,841				0.9
Repurchase Agreement					1,535,000				0.3
				$	528,164,866				100.2	%

See Notes to Financial Statements

10

Morgan Stanley Developing Growth Securities Trust

Financial Statements

Statement of Assets and Liabilities

March 31, 2006 (unaudited)

Assets:
Investments in securities, at value
(cost $407,361,926)				$	528,164,866
Receivable for:
Shares of beneficial interest sold					262,781
Investments sold					171,881
Dividends					127,084
Prepaid expenses and other assets					14,261
Receivable from affiliate					5,933
Total Assets					528,746,806
Liabilities:
Payable for:
Shares of beneficial interest redeemed					734,371
Distribution fee					232,599
Investment advisory fee					184,117
Transfer agent fee					44,671
Administration fee					35,139
Accrued expenses and other payables					144,127
Total Liabilities					1,375,024
Net Assets				$	527,371,782
Composition of Net Assets:
Paid-in-capital				$	523,117,425
Net unrealized appreciation					120,802,940
Accumulated net investment loss					(782,454	)
Accumulated net realized loss					(115,766,129	)
Net Assets				$	527,371,782
Class A Shares:
Net Assets				$	295,858,327
Shares Outstanding (unlimited authorized, $.01 par value)					10,155,752
Net Asset Value Per Share				$	29.13
Maximum Offering Price Per Share,
(net asset value plus 5.54% of net asset value)				$	30.74
Class B Shares:
Net Assets				$	174,022,022
Shares Outstanding (unlimited authorized, $.01 par value)					6,482,583
Net Asset Value Per Share				$	26.84
Class C Shares:
Net Assets				$	30,205,461
Shares Outstanding (unlimited authorized, $.01 par value)					1,121,344
Net Asset Value Per Share				$	26.94
Class D Shares:
Net Assets				$	27,285,972
Shares Outstanding (unlimited authorized, $.01 par value)					915,229
Net Asset Value Per Share				$	29.81

Statement of Operations

For the six months ended March 31, 2006 (unaudited)

Net Investment Loss:
Income
Dividends (net of $7,559 foreign withholding tax)				$	2,571,760
Interest					148,502
Total Income					2,720,262
Expenses
Investment advisory fee					1,084,372
Distribution fee (Class A shares)					320,345
Distribution fee (Class B shares)					861,030
Distribution fee (Class C shares)					143,320
Transfer agent fees and expenses					629,208
Administration fee					206,999
Shareholder reports and notices					81,344
Professional fees					37,843
Registration fees					26,721
Custodian fees					19,763
Trustees' fees and expenses					7,033
Other					22,191
Total Expenses					3,440,169
Net Investment Loss					(719,907	)
Net Realized and Unrealized Gain:
Net realized gain					39,965,863
Net change in unrealized appreciation					36,126,773
Net Gain					76,092,636
Net Increase				$	75,372,729

See Notes to Financial Statements

11

Morgan Stanley Developing Growth Securities Trust

Financial Statements continued

Statements of Changes in Net Assets

				FOR THE SIX MONTHS ENDED MARCH 31, 2006				FOR THE YEAR ENDED SEPTEMBER 30, 2005
				(unaudited)
Increase (Decrease) in Net Assets:
Operations:
Net investment loss				$	(719,907	)		$	(5,606,818	)
Net realized gain					39,965,863				109,295,803
Net change in unrealized appreciation					36,126,773				26,077,804
Net Increase					75,372,729				129,766,789
Net decrease from transactions in shares of beneficial interest					(100,243,806	)			(130,922,102	)
Net Decrease					(24,871,077	)			(1,155,313	)
Net Assets:
Beginning of period					552,242,859				553,398,172
End of Period (Including accumulated net investment losses of $782,454 and $62,547, respectively)				$	527,371,782			$	552,242,859

See Notes to Financial Statements

12

Morgan Stanley Developing Growth Securities Trust

Notes to Financial Statements March 31, 2006 (unaudited)

1.   Organization and Accounting Policies

Morgan Stanley Developing Growth Securities Trust (the ‘‘Fund’’) is registered under the Investment Company Act of 1940, as amended (the ‘‘Act’’), as a diversified, open-end management investment company. The Fund's investment objective is long-term capital growth. The Fund was organized as a Massachusetts business trust on December 28, 1982 and commenced operations on April 29, 1983. On July 28, 1997, the Fund converted to a multiple class share structure.

The Fund offers Class A shares, Class B shares, Class C shares and Class D shares. The four classes are substantially the same except that most Class A shares are subject to a sales charge imposed at the time of purchase and some Class A shares, and most Class B shares and Class C shares are subject to a contingent deferred sales charge imposed on shares redeemed within eighteen months, six years and one year, respectively. Class D shares are not subject to a sales charge. Additionally, Class A shares, Class B shares and Class C shares incur distribution expenses.

The Fund will assess a 2% redemption fee on Class A shares, Class B shares, Class C shares, and Class D shares, which is paid directly to the Fund, for shares redeemed within seven days of purchase, subject to certain exceptions. The redemption fee is designed to protect the Fund and its remaining shareholders from the effects of short-term trading.

The following is a summary of significant accounting policies:

A.   Valuation of Investments — (1) an equity portfolio security listed or traded on the New York Stock Exchange (‘‘NYSE’’) or American Stock Exchange or other exchange is valued at its latest sale price prior to the time when assets are valued; if there were no sales that day, the security is valued at the mean between the last reported bid and asked price; (2) an equity portfolio security listed or traded on the Nasdaq is valued at the Nasdaq Official Closing Price; if there were no sales that day, the security is valued at the mean between the last reported bid and asked price; (3) all other portfolio securities for which over-the-counter market quotations are readily available are valued at the mean between the last reported bid and asked price. In cases where a security is traded on more than one exchange, the security is valued on the exchange designated as the primary market; (4) for equity securities traded on foreign exchanges, the last reported sale price or the latest bid price may be used if there were no sales on a particular day; (5) when market quotations are not readily available or Morgan Stanley Investment Advisors Inc. (the ‘‘Investment Adviser’’) determines that the latest sale price, the bid price or the mean between the last reported bid and asked price do not reflect a security's market value, portfolio securities are valued at their fair value as determined in good faith under procedures established by and under the general supervision of the Fund’s Trustees. Occasionally, developments affecting the closing prices of securities and other assets may occur between the times at which valuations of such securities are determined (that is, close of the foreign market on which the securities trade) and the close of business on the NYSE. If developments occur during such periods that are

13

Morgan Stanley Developing Growth Securities Trust

Notes to Financial Statements March 31, 2006 (unaudited) continued

expected to materially affect the value of such securities, such valuations may be adjusted to reflect the estimated fair value of such securities as of the close of the NYSE, as determined in good faith by the Fund’s Trustees or by the Investment Adviser using a pricing service and/or procedures approved by the Trustees of the Fund; (6) certain portfolio securities may be valued by an outside pricing service approved by the Fund’s Trustees; and (7) short-term debt securities having a maturity date of more than sixty days at time of purchase are valued on a mark-to-market basis until sixty days prior to maturity and thereafter at amortized cost based on their value on the 61st day. Short-term debt securities having a maturity date of sixty days or less at the time of purchase are valued at amortized cost.

B.   Accounting for Investments — Security transactions are accounted for on the trade date (date the order to buy or sell is executed). Realized gains and losses on security transactions are determined by the identified cost method. Dividend income and other distributions are recorded on the ex-dividend date. Discounts are accreted and premiums are amortized over the life of the respective securities. Interest income is accrued daily.

C.   Repurchase Agreements — Pursuant to an Exemptive Order issued by the Securities and Exchange Commission, the Fund, along with other affiliated entities managed by the Investment Adviser, may transfer uninvested cash balances into one or more joint repurchase agreement accounts. These balances are invested in one or more repurchase agreements and are collateralized by cash, U.S. Treasury or federal agency obligations. The Fund may also invest directly with institutions in repurchase agreements. The Fund’s custodian receives the collateral, which is marked-to-market daily to determine that the value of the collateral does not decrease below the repurchase price plus accrued interest.

D.   Multiple Class Allocations — Investment income, expenses (other than distribution fees), and realized and unrealized gains and losses are allocated to each class of shares based upon the relative net asset value on the date such items are recognized. Distribution fees are charged directly to the respective class.

E.   Foreign Currency Translation and Forward Foreign Currency Contracts — The books and records of the Fund are maintained in U.S. dollars as follows: (1) the foreign currency market value of investment securities, other assets and liabilities and forward foreign currency contracts (‘‘forward contracts’’) are translated at the exchange rates prevailing at the end of the period; and (2) purchases, sales, income and expenses are translated at the exchange rates prevailing on the respective dates of such transactions. The resultant exchange gains and losses are recorded as realized and unrealized gain/loss on foreign exchange transactions. Pursuant to U.S. federal income tax regulations, certain foreign exchange gains/losses included in realized and unrealized gain/loss are included in or are a reduction of ordinary income for federal income tax purposes. The Fund does not isolate that portion of the results of operations arising as a result of changes in the foreign exchange rates from the changes in the market prices of the securities. Forward contracts are valued daily at the appropriate exchange rates. The resultant unrealized exchange gains and

14

Morgan Stanley Developing Growth Securities Trust

Notes to Financial Statements March 31, 2006 (unaudited) continued

losses are recorded as unrealized foreign currency gain or loss. The Fund records realized gains or losses on delivery of the currency or at the time the forward contract is extinguished (compensated) by entering into a closing transaction prior to delivery.

F.   Federal Income Tax Policy — It is the Fund's policy to comply with the requirements of the Internal Revenue Code applicable to regulated investment companies and to distribute substantially all of its taxable income to its shareholders. Accordingly, no federal income tax provision is required.

G.   Dividends and Distributions to Shareholders — Dividends and distributions to shareholders are recorded on the ex-dividend date.

H.   Use of Estimates — The preparation of financial statements in accordance with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts and disclosures. Actual results could differ from those estimates.

2.   Investment Advisory/Administration Agreements

Pursuant to an Investment Advisory Agreement, the Fund pays the Investment Adviser an advisory fee, accrued daily and payable monthly, by applying the following annual rates to the net assets of the Fund determined at the close of each business day: 0.42% to the portion of the daily net assets not exceeding $500 million and 0.395% to the portion of the daily net assets exceeding $500 million.

Pursuant to an Administration Agreement with Morgan Stanley Services Company Inc. (the ‘‘Administrator’’), an affiliate of the Investment Adviser, the Fund pays an administration fee, accrued daily and payable monthly, by applying the annual rate of 0.08% to the Fund’s daily net assets.

Effective November 18, 2005, the Investment Adviser has agreed to cap the Fund’s operating expenses (except for brokerage and 12b-1 fees) for one year by assuming the Fund’s ‘‘other expenses’’ and/or waiving the Fund’s advisory fees, and the Administrator has agreed to waive the Fund’s administrative fees, to the extent such operating expenses on an annualized basis exceed 0.87% of the average daily net assets of the Fund.

3.   Plan of Distribution

Shares of the Fund are distributed by Morgan Stanley Distributors Inc. (the ‘‘Distributor’’), an affiliate of the Investment Adviser and Administrator. The Fund has adopted a Plan of Distribution (the ‘‘Plan’’) pursuant to Rule 12b-1 under the Act. The Plan provides that the Fund will pay the Distributor a fee which is accrued daily and paid monthly at the following annual rates: (i) Class A – up to 0.25% of the average daily net assets of Class A; (ii) Class B – up to 1.0% of the lesser of: (a) the average daily aggregate gross sales of the Class B shares since the inception of the Fund (not including reinvestment of dividend or capital gain distributions) less the average daily aggregate net asset value of the Class B shares redeemed since the Fund's inception upon

15

Morgan Stanley Developing Growth Securities Trust

Notes to Financial Statements March 31, 2006 (unaudited) continued

which a contingent deferred sales charge has been imposed or waived; or (b) the average daily net assets of Class B; and (iii) Class C – up to 1.0% of the average daily net assets of Class C.

In the case of Class B shares, provided that the Plan continues in effect, any cumulative expenses incurred by the Distributor but not yet recovered may be recovered through the payment of future distribution fees from the Fund pursuant to the Plan and contingent deferred sales charges paid by investors upon redemption of Class B shares. Although there is no legal obligation for the Fund to pay expenses incurred in excess of payments made to the Distributor under the Plan and the proceeds of contingent deferred sales charges paid by investors upon redemption of shares, if for any reason the Plan is terminated, the Trustees will consider at that time the manner in which to treat such expenses. The Distributor has advised the Fund that such excess amounts totaled $30,119,453 at March 31, 2006.

In the case of Class A shares and Class C shares, expenses incurred pursuant to the Plan in any calendar year in excess of 0.25% or 1.0% of the average daily net assets of Class A or Class C, respectively, will not be reimbursed by the Fund through payments in any subsequent year, except that expenses representing a gross sales credit to Morgan Stanley Financial Advisors or other selected broker-dealer representatives may be reimbursed in the subsequent calendar year. For the six months ended March 31, 2006, the distribution fee was accrued for Class A shares and Class C shares at the annual rate of 0.23% and 0.99%, respectively.

The Distributor has informed the Fund that for the six months ended March 31, 2006, it received contingent deferred sales charges from certain redemptions of the Fund's Class A shares, Class B shares and Class C shares of $180, $172,164 and $820, respectively and received $97,596 in front-end sales charges from sales of the Fund's Class A shares. The respective shareholders pay such charges which are not an expense of the Fund.

4.   Security Transactions and Transactions with Affiliates

The cost of purchases and proceeds from sales of portfolio securities, excluding short-term investments, for the six months ended March 31, 2006 aggregated $156,716,936 and $251,005,765, respectively. Included in the aforementioned transactions are purchases and sales of $1,830,725, and $58,980,675, respectively for portfolio transactions with other Morgan Stanley funds, including realized gains of $16,938,231.

At March 31, 2006, Morgan Stanley Multi-Asset Class Fund, an affiliate of the Investment Adviser, Administrator and Distributor held 87,735 Class D shares of beneficial interest of the Fund.

Morgan Stanley Trust, an affiliate of the Investment Adviser, Administrator and Distributor, is the Fund's transfer agent.

For the six months ended March 31, 2006, the Fund incurred brokerage commissions of $1,725 with Morgan Stanley & Co., an affiliate of the Investment Adviser, Administrator and Distributor, for portfolio transactions executed on behalf of the Fund.

16

Morgan Stanley Developing Growth Securities Trust

Notes to Financial Statements March 31, 2006 (unaudited) continued

The Fund has an unfunded noncontributory defined benefit pension plan covering certain independent Trustees of the Fund who will have served as independent Trustees for at least five years at the time of retirement. Benefits under this plan are based on factors which include years of service and compensation. The Trustees voted to close the plan to new participants and eliminate the future benefits growth due to increases to compensation after July 31, 2003. Aggregate pension costs for the six months ended March 31, 2006 included in Trustees' fees and expenses in the Statement of Operations amounted to $3,702. At March 31, 2006, the Fund had an accrued pension liability of $63,999 which is included in accrued expenses in the Statement of Assets and Liabilities.

The Fund has an unfunded Deferred Compensation Plan (the ‘‘Compensation Plan’’) which allows each independent Trustee to defer payment of all, or a portion, of the fees he receives for serving on the Board of Trustees. Each eligible Trustee generally may elect to have the deferred amounts credited with a return equal to the total return on one or more of the Morgan Stanley funds that are offered as investment options under the Compensation Plan. Appreciation/depreciation and distributions received from these investments are recorded with an offsetting increase/decrease in the deferred compensation obligation and do not affect the net asset value of the Fund.

5.   Federal Income Tax Status

The amount of dividends and distributions from net investment income and net realized capital gains are determined in accordance with federal income tax regulations which may differ from generally accepted accounting principles. These ‘‘book/tax’’ differences are either considered temporary or permanent in nature. To the extent these differences are permanent in nature, such amounts are reclassified within the capital accounts based on their federal tax-basis treatment; temporary differences do not require reclassification. Dividends and distributions which exceed net investment income and net realized capital gains for tax purposes are reported as distributions of paid-in-capital.

As of September 30, 2005, the Fund had a net capital loss carryforward of $155,457,730 of which $5,745,285 will expire on September 30, 2009, $80,885,417 will expire on September 30, 2010, and $68,827,028 will expire on September 30, 2011 to offset future capital gains to the extent provided by regulations.

As of September 30, 2005, the Fund had temporary book/tax differences primarily attributable to capital loss deferrals on wash sales.

17

Morgan Stanley Developing Growth Securities Trust

Notes to Financial Statements March 31, 2006 (unaudited) continued

6.   Shares of Beneficial Interest

				FOR THE SIX MONTHS ENDED MARCH 31, 2006								FOR THE YEAR ENDED SEPTEMBER 30, 2005
				(unaudited)
				SHARES				AMOUNT				SHARES				AMOUNT
CLASS A SHARES
Sold					526,462			$	14,340,492				646,494			$	14,487,891
Conversion from Class B					310,858				8,353,474				9,019,623				190,510,634
Redeemed					(1,122,469	)			(30,121,391	)			(1,711,366	)			(39,172,267	)
Net increase (decrease) – Class A					(285,149	)			(7,427,425	)			7,954,751				165,826,258
CLASS B SHARES
Sold					253,525				6,348,678				546,062				11,237,204
Conversion to Class A					(336,740	)			(8,353,474	)			(9,718,063	)			(190,510,634	)
Redeemed					(933,993	)			(23,081,581	)			(4,409,548	)			(90,363,370	)
Net decrease – Class B					(1,017,208	)			(25,086,377	)			(13,581,549	)			(269,636,800	)
CLASS C SHARES
Sold					53,263				1,333,833				57,351				1,179,943
Redeemed					(162,229	)			(4,012,485	)			(401,860	)			(8,391,956	)
Net decrease – Class C					(108,966	)			(2,678,652	)			(344,509	)			(7,212,013	)
CLASS D SHARES
Sold					71,093				1,939,919				300,659				6,771,607
Redeemed					(2,491,778	)			(66,991,271	)			(1,166,769	)			(26,671,154	)
Net decrease – Class D					(2,420,685	)			(65,051,352	)			(866,110	)			(19,899,547	)
Net decrease in Fund					(3,832,008	)		$	(100,243,806	)			(6,837,417	)		$	(130,922,102	)

7.   Purposes of and Risks Relating to Certain Financial Instruments

The Fund may enter into forward contracts for many purposes, including to facilitate settlement of foreign currency denominated portfolio transactions or to manage foreign currency exposure associated with foreign currency denominated securities.

Forward contracts involve elements of market risk in excess of the amounts reflected in the Statement of Assets and Liabilities. The Fund bears the risk of an unfavorable change in the foreign exchange rates underlying the forward contracts. Risks may also arise upon entering into these contracts from the potential inability of the counterparties to meet the terms of their contracts.

18

Morgan Stanley Developing Growth Securities Trust

Notes to Financial Statements March 31, 2006 (unaudited) continued

8.   Legal Matters

The Investment Adviser, certain affiliates of the Investment Adviser, certain officers of such affiliates and certain investment companies advised by the Investment Adviser or its affiliates, including the Fund, are named as defendants in a consolidated class action. This consolidated action also names as defendants certain individual Trustees and Directors of the Morgan Stanley funds. The consolidated amended complaint, filed in the United States District Court Southern District of New York on April 16, 2004, generally alleges that defendants, including the Fund, violated their statutory disclosure obligations and fiduciary duties by failing properly to disclose (i) that the Investment Adviser and certain affiliates of the Investment Adviser allegedly offered economic incentives to brokers and others to recommend the funds advised by the Investment Adviser or its affiliates to investors rather than funds managed by other companies, and (ii) that the funds advised by the Investment Adviser or its affiliates, including the Fund, allegedly paid excessive commissions to brokers in return for their efforts to recommend these funds to investors. The complaint seeks, among other things, unspecified compensatory damages, rescissionary damages, fees and costs. The defendants have moved to dismiss the action. On March 9, 2005, Plaintiffs sought leave to supplement their complaint to assert claims on behalf of other investors, which motion defendants opposed. On April 14, 2006, the Court granted defendants' motion to dismiss in its entirety. Additionally, the Court denied Plaintiffs' motion to supplement their complaint. This matter is now concluded.

19

Morgan Stanley Developing Growth Securities Trust

Financial Highlights

Selected ratios and per share data for a share of beneficial interest outstanding throughout each period:

				FOR THE SIX MONTHS ENDED MARCH 31, 2006				FOR THE YEAR ENDED SEPTEMBER 30,
								2005				2004				2003				2002				2001
				(unaudited)
Class A Shares
Selected Per Share Data:
Net asset value, beginning of period				$	25.18			$	19.83			$	16.53			$	12.52			$	15.20			$	37.74
Income (loss) from investment operations:
Net investment loss‡					0.00				(0.14	)			(0.12	)			(0.09	)			(0.11	)			0.00
Net realized and unrealized gain (loss)					3.95				5.49				3.42				4.10				(2.57	)			(14.40	)
Total income (loss) from investment     operations					3.95				5.35				3.30				4.01				(2.68	)			(14.40	)
Less distributions from net realized gain					—				—				—				—				—				(8.14	)
Net asset value, end of period				$	29.13			$	25.18			$	19.83			$	16.53			$	12.52			$	15.20
Total Return†					15.69	%(1)			26.98	%			19.96	%			32.03	%			(17.63	)%			(45.93	)%
Ratios to Average Net Assets(3):
Expenses					1.05	%(2)			1.09	%			1.01	%(4)			1.06	%			1.02	%			0.88	%
Net investment loss					0.00	%(2)			(0.61	)%			(0.62	)%(4)			(0.62	)%			(0.68	)%			0.00	%
Supplemental Data:
Net assets, end of period, in thousands					$295,858				$262,913				$49,312				$25,111				$14,826				$17,906
Portfolio turnover rate					30	%(1)			115	%			149	%			202	%			237	%			213	%

‡ The per share amounts were computed using an average number of shares outstanding during the period.

† Does not reflect the deduction of sales charge. Calculated based on the net asset value as of the last business day of the period.

(1) Not annualized.

(2) Annualized.

(3) Reflects overall Fund ratios for investment income and non-class specific expenses.

(4) If the Investment Adviser had not waived part of its investment advisory fee, the ratios of expenses and net investment loss to average net assets would have been 1.04% and (0.65)%, respectively.

See Notes to Financial Statements

20

Morgan Stanley Developing Growth Securities Trust

Financial Highlights continued

				FOR THE SIX MONTHS ENDED MARCH 31, 2006				FOR THE YEAR ENDED SEPTEMBER 30,
								2005				2004				2003				2002				2001
				(unaudited)
Class B Shares
Selected Per Share Data:
Net asset value, beginning of period				$	23.29			$	18.49			$	15.53			$	11.86			$	14.51			$	36.70
Income (loss) from investment operations:
Net investment loss‡					(0.09	)			(0.28	)			(0.24	)			(0.19	)			(0.23	)			(0.18	)
Net realized and unrealized gain (loss)					3.64				5.08				3.20				3.86				(2.42	)			(13.87	)
Total income (loss) from investment     operations					3.55				4.80				2.96				3.67				(2.65	)			(14.05	)
Less distributions from net realized gain					—				—				—				—				—				(8.14	)
Net asset value, end of period				$	26.84			$	23.29			$	18.49			$	15.53			$	11.86			$	14.51
Total Return†					15.24	%(1)			25.96	%			19.06	%			30.94	%			(18.26	)%			(46.37	)%
Ratios to Average Net Assets(3):
Expenses					1.82	%(2)			1.85	%			1.78	%(4)			1.87	%			1.80	%			1.70	%
Net investment loss					(0.77	)%(2)			(1.37	)%			(1.39	)%(4)			(1.43	)%			(1.46	)%			(0.82	)%
Supplemental Data:
Net assets, end of period, in thousands					$174,022				$174,688				$389,848				$293,619				$276,387				$443,652
Portfolio turnover rate					30	%(1)			115	%			149	%			202	%			237	%			213	%

‡ The per share amounts were computed using an average number of shares outstanding during the period.

† Does not reflect the deduction of sales charge. Calculated based on the net asset value as of the last business day of the period.

(1) Not annualized.

(2) Annualized.

(3) Reflects overall Fund ratios for investment income and non-class specific expenses.

(4) If the Investment Adviser had not waived part of its investment advisory fee, the ratios of expenses and net investment loss to average net assets would have been 1.81% and (1.42)%, respectively.

See Notes to Financial Statements

21

Morgan Stanley Developing Growth Securities Trust

Financial Highlights continued

				FOR THE SIX MONTHS ENDED MARCH 31, 2006				FOR THE YEAR ENDED SEPTEMBER 30,
								2005				2004				2003				2002				2001
				(unaudited)
Class C Shares
Selected Per Share Data:
Net asset value, beginning of period				$	23.37			$	18.55			$	15.57			$	11.88			$	14.54			$	36.76
Income (loss) from investment operations:
Net investment loss‡					(0.09	)			(0.28	)			(0.24	)			(0.19	)			(0.23	)			(0.18	)
Net realized and unrealized gain (loss)					3.66				5.10				3.22				3.88				(2.43	)			(13.90	)
Total income (loss) from investment     operations					3.57				4.82				2.98				3.69				(2.66	)			(14.08	)
Less distributions from net realized gain					—				—				—				—				—				(8.14	)
Net asset value, end of period				$	26.94			$	23.37			$	18.55			$	15.57			$	11.88			$	14.54
Total Return†					15.28	%(1)			25.98	%			19.14	%			31.06	%			(18.29)	%			(46.37)	%
Ratios to Average Net Assets(3):
Expenses					1.81	%(2)			1.81	%			1.78	%(4)			1.82	%			1.80	%			1.70	%
Net investment loss					(0.76	)%(2)			(1.33	)%			(1.39	)%(4)			(1.38	)%			(1.46	)%			(0.82	)%
Supplemental Data:
Net assets, end of period, in thousands					$30,205				$28,754				$29,208				$6,912				$5,986				$7,793
Portfolio turnover rate					30	%(1)			115	%			149	%			202	%			237	%			213	%

‡ The per share amounts were computed using an average number of shares outstanding during the period.

† Does not reflect the deduction of sales charge. Calculated based on the net asset value as of the last business day of the period.

(1) Not annualized.

(2) Annualized.

(3) Reflects overall Fund ratios for investment income and non-class specific expenses.

(4) If the Investment Adviser had not waived part of its investment advisory fee, the ratios of expenses and net investment loss to average net assets would have been 1.81% and (1.42)%, respectively.

See Notes to Financial Statements

22

Morgan Stanley Developing Growth Securities Trust

Financial Highlights continued

				FOR THE SIX MONTHS ENDED MARCH 31, 2006				FOR THE YEAR ENDED SEPTEMBER 30,
								2005				2004				2003				2002				2001
				(unaudited)
Class D Shares
Selected Per Share Data:
Net asset value, beginning of period				$	25.75			$	20.24			$	16.83			$	12.72			$	15.41			$	38.07
Income (loss) from investment operations:
Net investment income (loss)‡					0.00				(0.08	)			(0.07	)			(0.06	)			(0.07	)			0.03
Net realized and unrealized gain (loss)					4.06				5.59				3.48				4.17				(2.62	)			(14.55	)
Total income (loss) from investment     operations					4.06				5.51				3.41				4.11				(2.69	)			(14.52	)
Less distributions form net realized gain					—				—				—				—				—				(8.14	)
Net asset value, end of period				$	29.81			$	25.75			$	20.24			$	16.83			$	12.72			$	15.41
Total Return†					15.77	%(1)			27.22	%			20.26	%			32.31	%			(17.46	)%			(45.83	)%
Ratios to Average Net Assets(3):
Expenses					0.82	%(2)			0.85	%			0.78	%(4)			0.87	%			0.80	%			0.70	%
Net investment income (loss)					0.23	%(2)			(0.37	)%			(0.39	)%(4)			(0.43	)%			(0.46	)%			0.18	%
Supplemental Data:
Net assets, end of period, in thousands					$27,286				$85,887				$85,031				$104,190				$62,606				$57,436
Portfolio turnover rate					30	%(1)			115	%			149	%			202	%			237	%			213	%

‡ The per share amounts were computed using an average number of shares outstanding during the period.

† Calculated based on the net asset value as of the last business day of the period.

(1) Not annualized.

(2) Annualized.

(3) Reflects overall Fund ratios for investment income and non-class specific expenses.

(4) If the Investment Adviser had not waived part of its investment advisory fee, the ratios of expenses and net investment loss to average net assets would have been 0.81% and (0.42)%, respectively.

See Notes to Financial Statements

23

Trustees Michael Bozic Charles A. Fiumefreddo Edwin J. Garn Wayne E. Hedien James F. Higgins Dr. Manuel H. Johnson Joseph J. Kearns Michael E. Nugent Fergus Reid Officers Charles A. Fiumefreddo Chairman of the Board Ronald E. Robison President and Principal Executive Officer J. David Germany Vice President Dennis F. Shea Vice President Barry Fink Vice President Amy R. Doberman Vice President Carsten Otto Chief Compliance Officer Stefanie V. Chang Yu Vice President Francis J. Smith Treasurer and Chief Financial Officer Thomas F. Caloia Vice President Mary E. Mullin Secretary Transfer Agent Morgan Stanley Trust Harborside Financial Center, Plaza Two Jersey City, New Jersey 07311 Independent Registered Public Accounting Firm Deloitte & Touche LLP Two World Financial Center New York, New York 10281 Investment Adviser Morgan Stanley Investment Advisors Inc. 1221 Avenue of the Americas New York, New York 10020 The financial statements included herein have been taken from the records of the Fund without examination by the independent auditors and accordingly they do not express an opinion thereon. This report is submitted for the general information of the shareholders of the Fund. For more detailed information about the Fund, its fees and expenses and other pertinent information, please read its Prospectus. The Fund's Statement of Additional Information contains additional information about the Fund, including its trustees. It is available, without charge, by calling (800) 869-NEWS. This report is not authorized for distribution to prospective investors in the Fund unless preceded or accompanied by an effective Prospectus. Read the Prospectus carefully before investing. Investments and services offered through Morgan Stanley DW Inc., member SIPC. Morgan Stanley Distributors Inc., member NASD. © 2006 Morgan Stanley 37905RPTRA06-00401P-Y03/06		MORGAN STANLEY FUNDS
		Morgan Stanley Developing Growth Securities Trust Semiannual Report March 31, 2006

Item 2.  Code of Ethics.

Not applicable for semiannual reports.


Item 3.  Audit Committee Financial Expert.

Not applicable for semiannual reports.


Item 4. Principal Accountant Fees and Services

Not applicable for semiannual reports.


Item 5. Audit Committee of Listed Registrants.

Not applicable for semiannual reports.


Item 6.

Refer to Item 1.


Item 7. Disclosure of Proxy Voting Policies and Procedures for Closed-End
Management Investment Companies.

Not applicable for semiannual reports.


Item 8. Portfolio Managers of Closed-End Management Investment Companies

Applicable only to reports filed by closed-end funds.


Item 9. Closed-End Fund Repurchases

Applicable to reports filed by closed-end funds.


Item 10. Submission of Matters to a Vote of Security Holders

Not applicable.



Item 11. Controls and Procedures

(a) The Fund's principal executive officer and principal financial officer have
concluded that the Fund's disclosure controls and procedures are sufficient to
ensure that information required to be disclosed by the Fund in this Form N-CSR
was recorded, processed, summarized and reported within the time periods
specified in the Securities and Exchange Commission's rules and forms, based
upon such officers' evaluation of these controls and procedures as of a date
within 90 days of the filing date of the report.

(b) There were no changes in the registrant's internal control over financial
reporting that occurred during the second fiscal quarter of the period covered
by this report that has materially affected, or is reasonably likely to
materially affect, the registrant's internal control over financial reporting.


Item 12. Exhibits

(a) Code of Ethics - Not applicable for semiannual reports.

(b) A separate certification for each principal executive officer and principal
financial officer of the registrant are attached hereto as part of EX-99.CERT.















                                       2



                                   SIGNATURES

         Pursuant to the requirements of the Securities Exchange Act of 1934 and
the Investment Company Act of 1940, the registrant has duly caused this report
to be signed on its behalf by the undersigned, thereunto duly authorized.

Morgan Stanley Developing Growth Securities Trust

/s/ Ronald E. Robison
Ronald E. Robison
Principal Executive Officer
May 18, 2006

         Pursuant to the requirements of the Securities Exchange Act of 1934 and
the Investment Company Act of 1940, this report has been signed by the following
persons on behalf of the registrant and in the capacities and on the dates
indicated.

/s/ Ronald E. Robison
Ronald E. Robison
Principal Executive Officer
May 18, 2006

/s/ Francis Smith
Francis Smith
Principal Financial Officer
May 18, 2006





                                       3


                                                                   EXHIBIT 12 B1

                  CERTIFICATION OF PRINCIPAL EXECUTIVE OFFICER

                                 CERTIFICATIONS
                                 --------------

I, Ronald E. Robison, certify that:

1.   I have reviewed this report on Form N-CSR of Morgan Stanley Developing
     Growth Securities Trust;

2.   Based on my knowledge, this report does not contain any untrue statement of
     a material fact or omit to state a material fact necessary to make the
     statements made, in light of the circumstances under which such statements
     were made, not misleading with respect to the period covered by this
     report;

3.   Based on my knowledge, the financial statements and other financial
     information included in this report, fairly present in all material
     respects the financial condition, results of operations, changes in net
     assets, and cash flows (if the financial statements are required to include
     a statement of cash flows) of the registrant as of, and for, the periods
     presented in this report;

4.   The registrant's other certifying officers and I are responsible for
     establishing and maintaining disclosure controls and procedures (as defined
     in Rule 30a-3(c) under the Investment Company Act of 1940) and internal
     control over financial reporting (as defined in Rule 30a-3(d) under the
     Investment Company Act of 1940) for the registrant and have:

a)   designed such disclosure controls and procedures, or caused such disclosure
     controls and procedures to be designed under our supervision, to ensure
     that material information relating to the registrant, including its
     consolidated subsidiaries, is made known to us by others within those
     entities, particularly during the period in which this report is being
     prepared;

b)   designed such internal control over financial reporting, or caused such
     internal control over financial reporting to be designed under our
     supervision, to provide reasonable assurance regarding the reliability of
     financial reporting and the preparation of financial statements for
     external purposes in accordance with generally accepted accounting
     principles;

c)   evaluated the effectiveness of the registrant's disclosure controls and
     procedures and presented in this report our conclusions about the
     effectiveness of the disclosure controls and procedures, as of a date
     within 90 days prior to the filing date of this report based on such
     evaluation; and

d)   disclosed in this report any change in the registrant's internal control
     over financial reporting that occurred during the registrant's most recent
     fiscal half-year (the registrant's second fiscal half-year in the case of
     an annual report) that has materially affected, or is reasonably likely to
     materially affect, the registrant's internal control over financial
     reporting; and

5.   The registrant's other certifying officer(s) and I have disclosed to the
     registrant's auditors and the audit committee of the registrant's board of
     directors (or persons performing the equivalent functions):


                                       4


a)   all significant deficiencies and material weaknesses in the design or
     operation of internal control over financial reporting which are reasonably
     likely to adversely affect the registrant's ability to record, process,
     summarize, and report financial information; and

b)   any fraud, whether or not material, that involves management or other
     employees who have a significant role in the registrant's internal controls
     over financial reporting.

Date: May 18, 2006
                                                   /s/ Ronald E. Robison
                                                   Ronald E. Robison
                                                   Principal Executive Officer







                                       5



                                                                   EXHIBIT 12 B2

                  CERTIFICATION OF PRINCIPAL FINANCIAL OFFICER

                                 CERTIFICATIONS
                                 --------------

I, Francis Smith, certify that:

1.   I have reviewed this report on Form N-CSR of Morgan Stanley Developing
     Growth Securities Trust;

2.   Based on my knowledge, this report does not contain any untrue statement of
     a material fact or omit to state a material fact necessary to make the
     statements made, in light of the circumstances under which such statements
     were made, not misleading with respect to the period covered by this
     report;

3.   Based on my knowledge, the financial statements and other financial
     information included in this report, fairly present in all material
     respects the financial condition, results of operations, changes in net
     assets, and cash flows (if the financial statements are required to include
     a statement of cash flows) of the registrant as of, and for, the periods
     presented in this report;

4.   The registrant's other certifying officers and I are responsible for
     establishing and maintaining disclosure controls and procedures (as defined
     in Rule 30a-3(c) under the Investment Company Act of 1940) and internal
     control over financial reporting (as defined in Rule 30a-3(d) under the
     Investment Company Act of 1940) for the registrant and have:

a)   designed such disclosure controls and procedures, or caused such disclosure
     controls and procedures to be designed under our supervision, to ensure
     that material information relating to the registrant, including its
     consolidated subsidiaries, is made known to us by others within those
     entities, particularly during the period in which this report is being
     prepared;

b)   designed such internal control over financial reporting, or caused such
     internal control over financial reporting to be designed under our
     supervision, to provide reasonable assurance regarding the reliability of
     financial reporting and the preparation of financial statements for
     external purposes in accordance with generally accepted accounting
     principles;

c)   evaluated the effectiveness of the registrant's disclosure controls and
     procedures and presented in this report our conclusions about the
     effectiveness of the disclosure controls and procedures, as of a date
     within 90 days prior to the filing date of this report based on such
     evaluation; and

d)   disclosed in this report any change in the registrant's internal control
     over financial reporting that occurred during the registrant's most recent
     fiscal half-year (the registrant's second fiscal half-year in the case of
     an annual report) that has materially affected, or is reasonably likely to
     materially affect, the registrant's internal control over financial
     reporting; and

5.   The registrant's other certifying officer(s) and I have disclosed to the
     registrant's auditors and the audit committee of the registrant's board of
     directors (or persons performing the equivalent functions):

                                       6


a)   all significant deficiencies and material weaknesses in the design or
     operation of internal control over financial reporting which are reasonably
     likely to adversely affect the registrant's ability to record, process,
     summarize, and report financial information; and

b)   any fraud, whether or not material, that involves management or other
     employees who have a significant role in the registrant's internal controls
     over financial reporting.

Date: May 18, 2006
                                                  /s/ Francis Smith
                                                  Francis Smith
                                                  Principal Financial  Officer





                                       7



                            SECTION 906 CERTIFICATION

                Certification Pursuant to 18 U.S.C. Section 1350,
                             As Adopted Pursuant to
                  Section 906 of the Sarbanes-Oxley Act of 2002

Morgan Stanley Developing Growth Securities Trust

         In connection with the Report on Form N-CSR (the "Report") of the
above-named issuer for the period ended March 31, 2006 that is accompanied by
this certification, the undersigned hereby certifies that:

1.       The Report fully complies with the requirements of Section 13(a) or
         15(d) of the Securities Exchange Act of 1934; and

2.       The information contained in the Report fairly presents, in all
         material respects, the financial condition and results of operations of
         the Issuer.



Date: May 18, 2006                              /s/ Ronald E. Robison
                                                ---------------------
                                                Ronald E. Robison
                                                Principal Executive Officer


A signed original of this written statement required by Section 906 has been
provided to Morgan Stanley Developing Growth Securities Trust and will be
retained by Morgan Stanley Developing Growth Securities Trust and furnished to
the Securities and Exchange Commission or its staff upon request.








                                       8



                            SECTION 906 CERTIFICATION

                Certification Pursuant to 18 U.S.C. Section 1350,
                             As Adopted Pursuant to
                  Section 906 of the Sarbanes-Oxley Act of 2002

Morgan Stanley Developing Growth Securities Trust

         In connection with the Report on Form N-CSR (the "Report") of the
above-named issuer for the period ended March 31, 2006 that is accompanied by
this certification, the undersigned hereby certifies that:

1.       The Report fully complies with the requirements of Section 13(a) or
         15(d) of the Securities Exchange Act of 1934; and

2.       The information contained in the Report fairly presents, in all
         material respects, the financial condition and results of operations of
         the Issuer.



Date: May 18, 2006                                  /s/ Francis Smith
                                                    -------------------
                                                    Francis Smith
                                                    Principal Financial Officer


A signed original of this written statement required by Section 906 has been
provided to Morgan Stanley Developing Growth Securities Trust and will be
retained by Morgan Stanley Developing Growth Securities Trust and furnished to
the Securities and Exchange Commission or its staff upon request.






                                       9