April 2008 Preliminary Terms No. 596 Registration Statement No. 333-131266 Dated March 31, 2008 Filed pursuant to Rule 433

STRUCTURED INVESTMENTS

Opportunities in Equities

PLUS based on the S&P 500® Index due May 3, 2011

Performance Leveraged Upside SecuritiesSM

PLUS offer leveraged exposure to a wide variety of assets and asset classes, including equities, commodities and currencies.  These investments allow investors to capture enhanced returns relative to the asset’s actual positive performance.  At maturity, (i) if the asset has appreciated in value, investors will receive the stated principal amount of their investment plus unlimited leveraged upside performance of the underlying asset or (ii) if the asset has declined in value, investors will lose 1% for every 1% decline in the value of the asset.

SUMMARY TERMS
Issuer:	Morgan Stanley
Maturity date:	May 3, 2011
Underlying index:	S&P 500® Index
Aggregate principal amount:	$
Payment at maturity per PLUS:	§If final index value is greater than initial index value,
	$1,000 + ($1,000 x  upside leverage factor x index percent increase)
	§If final index value is less than or equal to initial index value,
	$1,000 x index performance factor
	This amount will be less than or equal to the stated principal amount of $1,000.
Index percent increase:	(final index value – initial index value) / initial index value
Initial index value:	The index closing value of the underlying index on the pricing date
Final index value:	The index closing value on the index valuation date
Index valuation date:	April 29, 2011, subject to adjustment for certain market disruption events
Upside leverage factor:	141% to 151%.  The actual upside leverage factor will be determined on the pricing date.
Index performance factor	final index value /initial index value
Maximum payment at maturity:	There is no maximum payment at maturity on the PLUS.
Stated principal amount:	$1,000 per PLUS
Issue price:	$1,000 per PLUS (see “Commissions and Issue Price” below)
Pricing date:	April      , 2008
Original issue date:	May      , 2008  (5 business days after the pricing date)
CUSIP:	6174465L9
Listing:	The PLUS will not be listed on any securities exchange.
Agent:	Morgan Stanley & Co. Incorporated

Commissions and Issue Price:		Price to Public	Agent’s Commissions(1)	Proceeds to Company
	Per PLUS	$1,000	$	$
	Total	$	$	$

 (1) For additional information, see “Plan of Distribution” in the prospectus supplement for PLUS.

You should read this document together with the related prospectus supplement and prospectus, each of which can be accessed via the hyperlinks below, before you decide to invest.

Amendment No. 2 to Prospectus Supplement for PLUS dated October 24, 2007

Prospectus dated January 25, 2006

The issuer has filed a registration statement (including a prospectus) with the SEC for the offering to which this communication relates.  Before you invest, you should read the prospectus in that registration statement and other documents the issuer has filed with the SEC for more complete information about the issuer and this offering.  You may get these documents for free by visiting EDGAR on the SEC Web site at www.sec.gov. Alternatively, the issuer, any underwriter or any dealer participating in the offering will arrange to send you the prospectus if you request it by calling toll-free 1-800-584-6837.

PLUS Based on the Value of the S&P 500® Index due May 3, 2011

Performance Leveraged Upside SecuritiesSM

Investment Overview

Performance Leveraged Upside Securities

The S&P 500® Index PLUS (the “PLUS”) can be used:

§   As an alternative to direct exposure to the underlying index that enhances returns for the positive performance of the underlying index

§   To enhance returns and outperform the underlying index in a bullish scenario with no limitation on appreciation potential

§   To achieve similar levels of upside exposure to the underlying index as a direct investment while using fewer dollars by taking advantage of the upside leverage factor

§   The PLUS are exposed on a 1:1 basis to the negative performance of the underlying index

Maturity:	3 years
Upside Leverage factor:	141% to 151%. The actual upside leverage factor will be determined on the pricing date.
Maximum payment at maturity:	There is no maximum payment at maturity on the PLUS
Principal protection:	None
Interest:	None

S&P 500® Index Overview

The S&P 500® Index, which is calculated, maintained and published by Standard & Poor’s® Corporation, consists of 500 component stocks selected to provide a performance benchmark for the U.S. equity markets.  The calculation of the S&P 500® Index is based on the relative value of the float adjusted aggregate market capitalization of the 500 component companies as of a particular time as compared to the aggregate average market capitalization of the 500 similar companies during the base period of the years 1941 through 1943.

Information as of market close on March 27, 2008:

Bloomberg Ticker:	SPX
Current Index Level:	1,325.76
52 Weeks Ago:	1,427.61
52 Week High(on 10/9/07):	1,565.15
52 Week Low (on 3/10/08):	1,273.37

Underlying Index Historical Performance – End of Week Values

January 3, 2003 to March 21, 2008

April 2008 Page 2

PLUS Based on the Value of the S&P 500® Index due May 3, 2011

Performance Leveraged Upside SecuritiesSM

Key Investment Rationale

This 3 year investment offers 141% to 151% leveraged upside with no maximum payment at maturity.

Investors can use the PLUS to gain upside exposure to the underlying index using fewer dollars because of the upside leverage factor, while maintaining similar risk as a direct investment in the underlying index.

Leverage Performance	The PLUS offer investors an opportunity to capture unlimited enhanced returns relative to a direct investment in the underlying index while maintaining a similar risk profile.
Best Case Scenario	The underlying index increases in value and, at maturity, the PLUS redeem for the stated principal amount of $1,000 plus 141% to 151% of the appreciation of the underlying index with no maximum payment at maturity.
Worst Case Scenario	The underlying index declines in value and, at maturity, the PLUS redeem for less than the stated principal amount by an amount proportionate to the decline.

Summary of Selected Key Risks (see page 8)

§   No guaranteed return of principal

§   No interest payments

§   The PLUS will not be listed on any exchange, secondary trading may be limited, and the inclusion of commissions and projected profit from hedging in the original issue price is likely to adversely affect secondary market prices and you could receive less, and possibly significantly less, than the stated principal amount per PLUS if you try to sell your PLUS prior to maturity.

§   The market price of the PLUS will be influenced by many unpredictable factors, including the value, volatility and dividend yield of the underlying index.

§   Investing in the PLUS is not equivalent to investing in the underlying index or the stocks composing the underlying index.

§   Adjustments to the underlying index by the underlying index publisher could adversely affect the value of the PLUS.

§   Economic interests of the calculation agent may be potentially adverse to investors.

§   The U.S. federal income tax consequences of an investment in the PLUS are uncertain.

§   Credit risk to Morgan Stanley

April 2008 Page 3

PLUS Based on the Value of the S&P 500® Index due May 3, 2011

Performance Leveraged Upside SecuritiesSM

Fact Sheet

The PLUS offered are senior unsecured obligations of Morgan Stanley, will pay no interest, do not guarantee any return of principal at maturity and have the terms described in the prospectus supplement for PLUS and the accompanying prospectus, as supplemented or modified by these preliminary terms.  At maturity, an investor will receive for each stated principal amount of PLUS that the investor holds, an amount in cash that may be greater than, equal to or less than the stated principal amount based upon the closing value of the underlying index at maturity.  The PLUS are senior notes issued as part of Morgan Stanley’s Series F Global Medium-Term Notes program.

Expected Key Dates
Pricing date:	Original issue date (settlement date):	Maturity date:
April   , 2008	May   , 2008 (5 business days after the pricing date)	May 3, 2011, subject to postponement due to a market disruption event
Key Terms
Issuer:	Morgan Stanley
Underlying index:	S&P 500® Index
Underlying index publisher:	Standard & Poor’s® Corporation
Issue price:	$1,000 per PLUS
Stated principal amount:	$1,000 per PLUS
Denominations:	$1,000 per PLUS and integral multiples thereof
Interest:	None
Bull market or bear market PLUS:	Bull market PLUS
Payment at maturity per PLUS:	§If final index value is greater than initial index value, $1,000 + ($1,000 x  upside leverage factor x index percent increase)
	§If final index value is less than or equal to initial index value,
	$1,000 x index performance factor
	This amount will be less than or equal to the stated principal amount of $1,000.
Upside Leverage factor:	141% to 151%. The actual upside leverage factor will be determined on the pricing date.
Index percent increase:	(final index value – initial index value) / initial index value
Initial index value:	The index closing value of the underlying index on the pricing date
Final index value:	The index closing value of the underlying index on the index valuation date as published on Bloomberg under the ticker symbol “SPX” or any successor symbol
Index valuation date:	April 29, 2011, subject to adjustment for certain market disruption events
Index performance factor:	(final index value / initial index value)
Maximum payment at maturity:	There is no maximum payment at maturity on the PLUS.
Postponement of maturity date:	If the scheduled index valuation date is not an index business day or if a market disruption event occurs on that day so that the index valuation date as postponed falls less than two scheduled index business days prior to the scheduled maturity date, the maturity date of the PLUS will be postponed until the second scheduled index business day following that index valuation date as postponed.
Risk factors:	Please see “Risk Factors” on page 8.

April 2008 Page 4

PLUS Based on the Value of the S&P 500® Index due May 3, 2011

Performance Leveraged Upside SecuritiesSM

General Information
Listing:	The PLUS will not be listed on any securities exchange.
CUSIP:	6174465L9
Tax considerations:	Although the issuer believes that, under current law, the PLUS should be treated as a single financial contract that is an “open transaction” for U.S. federal income tax purposes, there is uncertainty regarding the U.S. federal income tax consequences of an investment in the PLUS. Assuming this characterization of the PLUS is respected and subject to the discussion under “United States Federal Taxation” in the accompanying prospectus supplement for PLUS, the following U.S. federal income tax consequences should result based on current law: §A U.S. Holder (as defined in the accompanying prospectus supplement) should not be required to recognize taxable income over the term of the PLUS prior to maturity, other than pursuant to a sale or exchange. §Upon sale, exchange or settlement of the PLUS at maturity, a U.S. Holder should generally recognize capital gain or loss equal to the difference between the amount realized and the U.S. Holder’s tax basis in the PLUS.  Such gain or loss should generally be long-term capital gain or loss if the investor has held the PLUS for more than one year. On December 7, 2007, the Treasury Department and the Internal Revenue Service (the “IRS”) released a notice requesting comments on the U.S. federal income tax treatment of “prepaid forward contracts” and similar instruments, such as the PLUS.  The notice focuses in particular on whether to require holders of these instruments to accrue income over the term of their investment.  It also asks for comments on a number of related topics, including the character of income or loss with respect to these instruments; the relevance of factors such as the exchange-traded status of the instruments and the nature of the underlying property to which the instruments are linked; the degree, if any, to which income (including any mandated accruals) realized by non-U.S. investors should be subject to withholding tax; and whether these instruments are or should be subject to the “constructive ownership” regime, which very generally can operate to recharacterize certain long-term capital gain as ordinary income that is subject to an interest charge.  While the notice requests comments on appropriate transition rules and effective dates, any Treasury regulations or other guidance promulgated after consideration of these issues could materially and adversely affect the tax consequences of an investment in the PLUS, possibly with retroactive effect.  Both U.S. and Non-U.S. Holders (as defined in the accompanying prospectus supplement) should consult their tax advisers regarding the U.S. federal income tax consequences of an investment in the PLUS, including possible alternative treatments and the issues presented by this notice.
Trustee:	The Bank of New York (as successor trustee to JPMorgan Chase Bank, N.A.)
Calculation agent:	Morgan Stanley & Co. Incorporated (“MS & Co.”)
Use of proceeds and hedging:	The net proceeds we receive from the sale of the PLUS will be used for general corporate purposes and, in part, in connection with hedging our obligations under the PLUS through one or more of our subsidiaries.
	On or prior to the pricing date, we, through our subsidiaries or others, will hedge our anticipated exposure in connection with the PLUS by taking positions in futures and options contracts on the underlying index.  Such purchase activity could increase the value of the underlying index, and therefore the value at which the underlying index must close on the index valuation date before investors would receive at maturity a payment that exceeds the principal amount of the PLUS.  For further information on our use of proceeds and hedging, see “Use of Proceeds and Hedging” in the prospectus supplement for PLUS.
ERISA:	See “ERISA” in the prospectus supplement for PLUS.
Contact:	Morgan Stanley clients may contact their local Morgan Stanley branch office or our principal executive offices at 1585 Broadway, New York, New York 10036 (telephone number (866) 477-4776).  All other clients may contact their local brokerage representative.  Third-party distributors may contact Morgan Stanley Structured Investment Sales at (800) 233-1087.

This offering summary represents a summary of the terms and conditions of the PLUS.  We encourage you to read the accompanying prospectus supplement for PLUS and prospectus for this offering, which can be accessed via the hyperlinks on the front page of this document.

April 2008 Page 5

PLUS Based on the Value of the S&P 500® Index due May 3, 2011

Performance Leveraged Upside SecuritiesSM

How PLUS Work

Payoff Diagram

The payoff diagram below illustrates the payment at maturity on the PLUS based on the following terms:

Stated principal amount:	$1,000
Hypothetical upside leverage factor:	146%
Maximum payment at maturity:	There is no maximum payment at maturity on the PLUS.

PLUS Payoff Diagram

How it works

§   If the final index value is greater than the initial index value, then investors receive the $1,000 stated principal amount plus the hypothetical leverage factor of 146% of the appreciation of the underlying index over the term of the PLUS.  There is no maximum payment at maturity on the PLUS.

§  If the underlying index appreciates 5%, the investor would receive a 7.3% return, or $1,073.

§  If the final index value is less than or equal to the initial index value, the investor would receive an amount less than or equal to the $1,000 stated principal amount, based on a 1% loss of principal for each 1% decline in the underlying index.

§  If the underlying index depreciates 10%, the investor would lose 10% of their principal and receive only $900 at maturity, or 90% of the stated principal amount.

April 2008 Page 6

PLUS Based on the Value of the S&P 500® Index due May 3, 2011

Performance Leveraged Upside SecuritiesSM

Payment at Maturity

At maturity, investors will receive for each $1,000 stated principal amount of PLUS that they hold an amount in cash based upon the value of the underlying index, determined as follows:

If the final index value is greater than the initial index value:

$1,000+    Leveraged Upside Payment:

The actual upside leverage factor will be determined on the pricing date.

If the final index value is less than or equal to the initial index value:

$1,000    XIndex Performance Factor

Because the index performance factor will be less than or equal to 1.0, this payment will be less than or equal to $1,000.

April 2008 Page 7

PLUS Based on the Value of the S&P 500® Index due May 3, 2011

Performance Leveraged Upside SecuritiesSM

Risk Factors

The following is a non-exhaustive list of certain key risk factors for investors in the PLUS.  For further discussion of these and other risks, you should read the section entitled “Risk Factors” beginning on page S-18 of the prospectus supplement for PLUS.  We also urge you to consult your investment, legal, tax, accounting and other advisers before you invest in the PLUS.

Structure Specific Risk Factors

§   PLUS do not pay interest nor guarantee return of principal.  The terms of the PLUS differ from those of ordinary debt securities in that the PLUS do not pay interest nor guarantee payment of the principal amount at maturity.  If the final index value is less than the initial index value, the payout at maturity will be an amount in cash that is less than the $1,000 stated principal amount of each PLUS by an amount proportionate to the decrease in the value of the underlying index.

§   Market price influenced by many unpredictable factors.  Several factors will influence the value of the PLUS in the secondary market and the price at which MS & Co. may be willing to purchase or sell the PLUS in the secondary market, including: the value, volatility and dividend yield of the underlying index, interest and yield rates, time remaining to maturity, geopolitical conditions and economic, financial, political and regulatory or judicial events and creditworthiness of the issuer.

§   Not equivalent to investing in the underlying index.  Investing in the PLUS is not equivalent to investing in the underlying index or its component stocks.  Investors in the PLUS will not have voting rights or rights to receive dividends or other distributions or any other rights with respect to stocks that constitute the underlying index.

§   Adjustments to the underlying index could adversely affect the value of the PLUS.  The underlying index publisher may discontinue or suspend calculation or publication of the underlying index at any time.  In these circumstances, the calculation agent will have the sole discretion to substitute a successor index that is comparable to the discontinued underlying index and is not precluded from considering indices that are calculated and published by the calculation agent or any of its affiliates.

§   The inclusion of commissions and projected profit from hedging in the original issue price is likely to adversely affect secondary market prices.  Assuming no change in market conditions or any other relevant factors, the price, if any, at which MS & Co. is willing to purchase PLUS in secondary market transactions will likely be lower than the original issue price, since the original issue price included, and secondary market prices are likely to exclude, commissions paid with respect to the PLUS, as well as the projected profit included in the cost of hedging the issuer’s obligations under the PLUS.  In addition, any such prices may differ from values determined by pricing models used by MS & Co., as a result of dealer discounts, mark-ups or other transaction costs.

§   The U.S. federal income tax consequences of an investment in the PLUS are uncertain.  Please read the discussion under “Fact Sheet ― General Information ― Tax Considerations” in these preliminary terms and the discussion under “United States Federal Taxation” in the accompanying prospectus supplement for PLUS (together the “Tax Disclosure Sections”) concerning the U.S. federal income tax consequences of investing in the PLUS.  If the Internal Revenue Service (the “IRS”) were successful in asserting an alternative characterization or treatment for the PLUS, the timing and character of income on the PLUS might differ significantly from the tax treatment described in the Tax Disclosure Sections.  For example, under one characterization, U.S. Holders could be required to accrue original issue discount on the PLUS every year at a “comparable yield” determined at the time of issuance and recognize all income and gain in respect of the PLUS as ordinary income.  The issuer does not plan to request a ruling from the IRS regarding the tax treatment of the PLUS, and the IRS or a court may not agree with the tax treatment described in these preliminary terms and the accompanying prospectus supplement for PLUS.  On December 7, 2007, the Treasury Department and the IRS released a notice requesting comments on the U.S. federal income tax treatment of “prepaid forward contracts” and similar instruments, such as the PLUS.  The notice focuses in particular on whether to require holders of these instruments to accrue income over the term of their investment.  It also asks for comments on a number of related topics,

April 2008 Page 8

PLUS Based on the Value of the S&P 500® Index due May 3, 2011

Performance Leveraged Upside SecuritiesSM

including the character of income or loss with respect to these instruments; the relevance of factors such as the exchange-traded status of the instruments and the nature of the underlying property to which the instruments are linked; the degree, if any, to which income (including any mandated accruals) realized by non-U.S. investors should be subject to withholding tax; and whether these instruments are or should be subject to the “constructive ownership” regime, which very generally can operate to recharacterize certain long-term capital gain as ordinary income that is subject to an interest charge.  While the notice requests comments on appropriate transition rules and effective dates, any Treasury regulations or other guidance promulgated after consideration of these issues could materially and adversely affect the tax consequences of an investment in the PLUS, possibly with retroactive effect.  Both U.S. and Non-U.S. Holders should consult their tax advisers regarding the U.S. federal income tax consequences of an investment in the PLUS, including possible alternative treatments and the issues presented by this notice.

Other Risk Factors

§   PLUS will not be listed and secondary trading may be limited.  The PLUS will not be listed on any securities exchange.  Therefore, there may be little or no secondary market for the PLUS.  MS & Co. currently intends to act as a market maker for the PLUS but is not required to do so.  Even if there is a secondary market, it may not provide enough liquidity to allow you to trade or sell the PLUS easily.  Because we do not expect that other market makers will participate significantly in the secondary market for the PLUS, the price at which you may be able to trade your PLUS is likely to depend on the price, if any, at which MS & Co. is willing to transact.  If at any time MS & Co. were to cease acting as a market maker, it is likely that there would be no secondary market for the PLUS.

§   Potential adverse economic interest of the calculation agent.  The hedging or trading activities of the issuer’s affiliates on or prior to the pricing date and prior to maturity could adversely affect the value of the underlying index and, as a result, could decrease the amount an investor may receive on the PLUS at maturity.  Any of these hedging or trading activities on or prior to the pricing date could potentially affect the initial index value and, therefore, could increase the value at which the underlying index must close before an investor receives a payment at maturity that exceeds the issue price of the PLUS.  Additionally, such hedging or trading activities during the term of the PLUS, including on the index valuation date, could potentially affect the value of the underlying index on the index valuation date and, accordingly, the amount of cash an investor will receive at maturity.

§   Issuer’s credit ratings may affect the market value of the PLUS.  Investors are subject to the credit risk of the issuer.  Any decline in the issuer’s credit ratings may affect the market value of the PLUS.

April 2008 Page 9

PLUS Based on the Value of the S&P 500® Index due May 3, 2011

Performance Leveraged Upside SecuritiesSM

Information about the Underlying Index

The S&P 500® Index.  The S&P 500® Index, which is calculated, maintained and published by Standard & Poor's® Corporation, consists of 500 component stocks selected to provide a performance benchmark for the U.S. equity markets.  The S&P 500® Index is described under the heading “Underlying Indices and Underlying Index Publishers Information—S&P 500® Index” in Annex A of the accompanying prospectus supplement for PLUS.

License Agreement between Standard & Poor’s® Corporation and Morgan Stanley.  “Standard & Poor’s®,” “S&P®,” “S&P 500®,” “Standard & Poor’s 500” and “500” are trademarks of The McGraw-Hill Companies, Inc. and have been licensed for use by Morgan Stanley. See “Underlying Indices and Underlying Index Publishers Information—S&P 500® Index—License Agreement between S&P and Morgan Stanley” in Annex A of the accompanying prospectus supplement for PLUS.

Historical Information

The following table sets forth the published high and low closing values, as well as end-of-quarter closing values, of the underlying index for each quarter in the period from January 1, 2003 through March 27, 2008.  The closing value of the underlying index on March 27, 2008 was 1,325.76.  We obtained the information in the table below from Bloomberg Financial Markets, without independent verification.  The historical values of the underlying index should not be taken as an indication of future performance, and no assurance can be given as to the level of the underlying index on the index valuation date.  The payment of dividends on the stocks that constitute the underlying index are not reflected in its level and, therefore, have no effect on the calculation of the payment at maturity.

S&P 500® Index	High	Low	Period End
2003
First Quarter	931.66	800.73	848.18
Second Quarter	1,011.66	858.48	974.50
Third Quarter	1,039.58	965.46	995.97
Fourth Quarter	1,111.92	1,018.22	1,111.92
2004
First Quarter	1,157.76	1,091.33	1,126.21
Second Quarter	1,150.57	1,084.10	1,140.84
Third Quarter	1,129.30	1,063.23	1,114.58
Fourth Quarter	1,213.55	1,094.81	1,211.92
2005
First Quarter	1,225.31	1,163.75	1,180.59
Second Quarter	1,216.96	1,137.50	1,191.33
Third Quarter	1,245.04	1,194.44	1,228.81
Fourth Quarter	1,272.74	1,176.84	1,248.29
2006
First Quarter	1,307.25	1,254.78	1,294.83
Second Quarter	1,325.76	1,223.69	1,270.20
Third Quarter	1,339.15	1,234.49	1,335.85
Fourth Quarter	1,427.09	1,331.32	1,418.30
2007
First Quarter	1,459.68	1,374.12	1,420.86
Second Quarter	1,539.18	1,424.55	1,503.35
Third Quarter	1,553.08	1,406.70	1,526.75
Fourth Quarter	1,565.15	1,407.22	1,468.36
2008
First Quarter (through March 27, 2008)	1,447.16	1,273.37	1,325.76

April 2008 Page 10