PROSPECTUS Dated May 5, 1999 Pricing Supplement No. 66 to
PROSPECTUS SUPPLEMENT Registration Statement No. 333-75289
Dated May 6, 1999 April 27, 2000
Rule 424(b)(3)
Morgan Stanley Dean Witter & Co.
MEDIUM-TERM NOTES, SERIES C
Senior Floating Rate Notes
-----------------------
We will not redeem these Medium-Term Notes, Series C (Senior Floating Rate
Notes) prior to the maturity date. We describe the basic features of this type
of note in the section called "Description of Notes--Floating Rate Notes" in
the accompanying prospectus supplement, subject to and as modified by the
provisions described below.
Principal Amount: $150,000,000
Maturity Date: May 5, 2003
Interest Accrual
Date: May 5, 2000
Interest Payment
Dates: Each February 5, May 5,
August 5, and November
5, commencing August 5,
2000
Initial Interest Rate: To be determined on the
second business day
prior to the Original
Issue Date
Base Rate: Federal Funds Rate
Index Maturity: One Day
Spread
(Plus or Minus): Plus 0.44% per annum
Index Currency: N/A
Interest Payment
Period: Quarterly
Specified Currency: U.S. Dollars
Issue Price: 100%
Settlement Date
(Original Issue Date): May 5, 2000
Initial Interest Reset
Date: May 6, 2000
Interest Reset Dates: Each business day
Interest Reset Period: Daily
Interest Determination
Dates: The second business
day prior to each
interest reset date
Reporting Service: Telerate (Page 120)
Book Entry Note or
Certificated Note: Book Entry Note
Senior Note or
Subordinated Note: Senior Note
Agent: Morgan Stanley & Co.
Incorporated
Calculation Agent: The Chase Manhattan
Bank
Minimum Denomination: $1,000
CUSIP: 61745EPQ8
Terms not defined above have the meanings given to such terms in the
accompanying prospectus supplement.
MORGAN STANLEY DEAN WITTER
