CALCULATION OF REGISTRATION FEE
       
Title of Each Class of Securities Offered   Maximum Aggregate
Offering Price (1)
 

Amount of Registration
Fee


 
 
Euro Floating Rate Senior Bearer Notes Due 2013    $393,410,655   $42,094.94
         
(1)  The U.S. dollar equivalent of the maximum aggregate offering price has been calculated using an exchange rate of $1.3115 per 1 euro as of December 22, 2006.
   
PROSPECTUS Dated January 25, 2006 Pricing Supplement No. 172 to
PROSPECTUS SUPPLEMENT Registration Statement No. 333-131266
Dated January 25, 2006 Dated December 22, 2006
  Rule 424(b)(2)

GLOBAL MEDIUM-TERM NOTES, SERIES G
Euro Floating Rate Senior Bearer Notes Due 2013

     We, Morgan Stanley, may not redeem these Global Medium-Term Notes, Series G, Euro Floating Rate Senior Bearer Notes Due 2013 (the “notes”) prior to the maturity date thereof other than under the circumstances described under “Description of Notes—Tax Redemption” in the accompanying prospectus supplement.

     The notes offered hereby will accrue interest from December 1, 2006 and constitute a further issuance of, and will be consolidated with, the Global Medium-Term Notes, Series G, Euro Floating Rate Senior Bearer Notes Due 2013 of Morgan Stanley issued on March 1, 2006 and October 27, 2006, which we refer to as the “original notes,” and form a single series with those original notes. The issuance of these notes will increase the aggregate principal amount of the outstanding notes of this series to Euro 2,800,000,000. The notes will initially be issued in temporary global bearer form and will be designated by the temporary ISIN and temporary common code noted below. After an initial period required for tax certification, which we expect to be completed on or prior to February 12, 2007, we expect the notes offered hereby to be exchanged for notes in permanent global bearer form and to trade interchangeably with the original notes under the permanent ISIN and permanent common code noted below assigned to the original notes.

     Application will be made for the notes described herein to be admitted to the Official List of the Financial Services Authority (in its capacity as competent authority for the purposes of Part VI of the Financial Services and Markets Act 2000) and to trading on the gilt-edged and fixed-interest market of the London Stock Exchange plc. No assurance can be given that such applications will be granted.

     This document constitutes the pricing supplement relating to the issuances of notes described herein. Terms used herein shall be deemed to be defined as such for the purposes of the Conditions set forth in the Base Prospectus referred to above. This pricing supplement is supplemental to and must be read in conjunction with such Base Prospectus.

     We will issue the notes only in bearer form, which form is further described under “Description of Notes—Forms of Notes” in the accompanying prospectus supplement. You may not exchange notes in bearer form at any time for notes in registered form.

     We describe the basic features of the notes in the section of the accompanying prospectus supplement called “Description of Notes.” In addition, we describe the basic features of the notes in the section of the accompanying prospectus called “Description of Debt Securities—Floating Rate Debt Securities,” subject to and as modified by the provisions described below.

Principal Amount:   Euro 300,000,000   Interest Determination    
Maturity Date:   March 1, 2013    Dates:   The second TARGET
Settlement Date           Settlement Day immediately
     (Original Issue Date):   January 3, 2007       preceding each interest reset
Interest Accrual Date:   December 1, 2006       date
Issue Price:   99.99%. plus accrued   Reporting Service:   Telerate (Page 248)
    interest from and including   Initial Offering Date    
    December 1, 2006      for Tax Redemption:   February 22, 2006
Specified Currency:   Euro   Business Days:   London, TARGET Settlement
Redemption Percentage           Day and New York
     at Maturity:   100%   Calculation Agent:   JPMorgan Chase Bank, N.A.
Base Rate:   EURIBOR       (London Branch)
Spread (Plus or Minus):   Plus 0.33%   Agent:   Morgan Stanley & Co.
Index Maturity:   Three months       International Limited
Initial Interest Rate:   As determined by the   Minimum Denominations:   Euro 50,000 and integral
    Calculation Agent based on       multiples of Euro 1,000 in
    the Base Rate on the second       excess thereof
    TARGET Settlement Day   Temporary Common    
    immediately prior to the      Code:   028103972
    Interest Accrual Date.   Permanent Common    
Initial Interest Reset Date:   March 1, 2007      Code:   024583643
Interest Payment Dates:   Each March 1, June 1,   Temporary ISIN:   XS0281039726
    September 1 and December 1,   Permanent ISIN:   XS0245836431
    commencing March 1, 2007   Other Provisions:   None
Interest Payment Period:   Quarterly        
Interest Reset Dates:   Each interest payment date        
Interest Reset Period:   Quarterly        

Terms not defined herein have the meanings given to such terms in the accompanying prospectus supplement and prospectus, as applicable.

MORGAN STANLEY
ABN AMRO BANK N.V. BARCLAYS CAPITAL BNP PARIBAS






Supplemental Information Concerning Plan of Distribution

     We will issue these notes in temporary global bearer form with the temporary ISIN XS0281039726 and temporary common code 028103972. Once these notes have been exchanged for notes in permanent global bearer form, on or about February 12, 2007, they will be combined with our Global Medium-Term Notes, Series G, Euro Floating Rate Senior Bearer Notes Due 2013, issued on March 1, 2006 and October 27, 2006, with the ISIN XS0245836431 and the common code 024583643, and offered pursuant to pricing supplement No. 29, dated February 22, 2006 and pricing supplement No. 121 dated October 20, 2006, to the prospectus dated January 25, 2006 and the prospectus supplement dated January 25, 2006. Following the exchange, both these notes and the original notes, in a combined aggregate principal amount of Euro 2,800,000,000, will bear the ISIN XS0245836431 and the common code 024583643.

     On December 27, 2006, we agreed to sell to the managers listed in this pricing supplement, and they severally agreed to purchase, the principal amounts of notes set forth opposite their respective names below at a net price of 99.69%, plus accrued interest from and including December 1, 2006, which we refer to as the “purchase price”. The purchase price equals the stated issue price of 99.99%, plus accrued interest from and including December 1, 2006, less a combined management and underwriting commission of 0.30% of the principal amount of the notes.

Name   Principal Amount
of Notes

Morgan Stanley & Co. International Limited   Euro 291,000,000
ABN AMRO Bank N.V.   3,000,000
Barclays Bank PLC   3,000,000
BNP Paribas   3,000,000

Total   Euro 300,000,000

European Union Transparency Obligations Directive

     The proposed European Union Transparency Obligations Directive (the “Directive”) may be implemented in a manner which could be burdensome for companies such as us. In particular, we may be required to prepare financial statements in accordance with accounting standards other than U.S. GAAP. We are under no obligation to maintain the listing of the notes, and prospective purchasers of notes should be aware that, in circumstances where a listing of the notes by the UK Listing Authority would require preparation of financial statements in accordance with standards other than U.S. GAAP, or in any other circumstances where the Directive is implemented in a manner that, in our opinion, is burdensome, the notes may be de-listed. In such a case of de-listing, we may, but are not obliged to, seek an alternative listing for the notes on a stock exchange outside the European Union. However, if such an alternative listing is not available or is, in our opinion, burdensome, an alternative listing for the notes may not be considered. Although no assurance is made as to the liquidity of the notes as a result of listing by the UK Listing Authority, de-listing the notes may have a material effect on a noteholder’s ability to resell the notes in the secondary market.

PS-2