November 6, 2000


Morgan Stanley Dean Witter Diversified Income Trust
Two World Trade Center
New York, New York  10048

Ladies and Gentlemen:

     This opinion is being furnished to Morgan Stanley Dean Witter Diversified
Income Trust, a Massachusetts business trust ("Diversified Income "), in
connection with the Registration Statement on Form N-14 (the "Registration
Statement") under the Securities Act of 1933, as amended (the "1933 Act"), to be
filed by Diversified Income in connection with the acquisition by Diversified
Income, of substantially all the assets of Morgan Stanley Dean Witter World Wide
Income Trust, a Massachusetts business trust ("World Wide"), in exchange for
shares of beneficial interest of Diversified Income ("Shares") and the
assumption by Diversified Income of certain stated liabilities of World Wide
pursuant to an Agreement and Plan of Reorganization dated as of October 26, 2000
(the "Reorganization Agreement"). We have examined such statutes, regulations,
corporate records and other documents and reviewed such questions of law as we
deemed necessary or appropriate for the purposes of this opinion.

     As to matters of Massachusetts law contained in this opinion, we have
relied upon the opinion of Nutter, McClennen & Fish LLP, dated November 3, 2000.

     Based upon the foregoing, we are of the opinion that the Shares when
issued, as described in the Reorganization Agreement, will be duly authorized
and, assuming receipt of the consideration to be paid therefor, upon delivery as
provided in the Reorganization Agreement, will be legally issued, fully paid and
non-assessable (except for the potential liability of shareholders described in
Diversified Income's Statement of Additional Information dated February 3, 2000
under the caption "Capital Stock And Other Securities").

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to us under the caption "Legal
Matters" in the Prospectus forming a part of the Registration Statement. We do
not thereby admit that we are within the category of persons whose consent is
required under Section 7 of the 1933 Act or the rules and regulations of the
Securities and Exchange Commission thereunder.

                                         Very truly yours,


                                         /s/ Mayer, Brown & Platt