Exhibit 8-c

                              DAVIS POLK & WARDWELL
                              450 LEXINGTON AVENUE
                            NEW YORK, NEW YORK 10017




                                 (212) 450-4000


                                                   July 27, 2000


Morgan Stanley Dean Witter & Co.
1585 Broadway
New York, New York 10036

Re:  Morgan Stanley Dean Witter & Co., Issuance of Medium-Term Notes, Series C -
     Senior Variable Rate Renewable Notes - $3,000,000,000 EXtendible Liquidity
     SecuritiesSM (EXLsSM)

Ladies and Gentlemen:

           We have acted as special tax counsel for Morgan Stanley Dean Witter &
Co. (the "Company") in connection with the issuance of $3,000,000,000 of the
Company's EXtendible Liquidity SecuritiesSM (EXLsSM), described in Pricing
Supplement No. 20 to Registration Statement No. 333-34392, dated July 21, 2000
(the "Pricing Supplement"). We have reviewed the discussion set forth under the
caption "United States Federal Taxation" in the Pricing Supplement and are of
the opinion that the discussion is accurate.

           We are members of the Bar of the State of New York. The foregoing
opinion is based upon and limited to the federal laws of the United States of
America as contained in the Internal Revenue Code of 1986, as amended, Treasury
regulations, administrative decisions and court decisions as of the date of this
letter.

           We hereby consent to the use of our name under the caption "United
States Federal Taxation" in the Pricing Supplement. The issuance of such a
consent does not concede that we are an "Expert" for the purposes of the
Securities Act of 1933.

                                                      Very truly yours,

                                                      /s/ Davis Polk & Wardwell