- Certification of no change in definitive materials. (497J)

Deutsche Investment Management Americas Inc.

One Beacon Street

Boston, MA 02108

May 4, 2010

Securities and Exchange Commission

100 F Street, N.E.

Washington, DC 20549

RE: DWS Money Market Series, (the “Fund”), a series of DWS Money Market Trust (the “Trust”) (Reg. Nos. 002-78122 and 811-03495)

Ladies and Gentlemen:

Pursuant to Rule 497(j) under the Securities Act of 1933, as amended, the Trust hereby certifies that the form of Prospectus and Statement of Additional Information that would have been filed on behalf of the Fund pursuant to Rule 497(c) upon the effectiveness of Post-Effective Amendment No. 48 to the Trust’s Registration Statement on form N-1A (the “Amendment”), does not differ from that contained in the Amendment, which is the most recent Registration Statement and was filed electronically on April 26, 2010.

Any comments or questions on this filing should be directed to the undersigned at (617) 295-3986.

Very truly yours,