Supplement to the currently effective  Statements of Additional  Information for
the below-listed fund.

DWS Money Market Prime Series

All references to securities  lending  practices in the Statements of Additional
Information  are hereby  revised to reflect the Board's  approval of  securities
lending by the Fund in an amount equal to 33 1/3% of its total assets.  Further,
the following additional changes are hereby made to each Statement of Additional
Information.

The following replaces similar language in the "Investment Restrictions" section
of the fund's Statements of Additional Information:

As a matter of  non-fundamental  policy,  the Fund  currently does not intend to
lend portfolio securities in an amount greater than 33 1/3% of its total assets.

The following supplements disclosure in the "Investment Policies and Techniques"
section of the fund's Statements of Additional Information:

Lending of Portfolio Securities.  The Fund may lend its investment securities to
approved  institutional  borrowers  who need to  borrow  securities  in order to
complete certain  transactions,  such as covering short sales, avoiding failures
to deliver  securities  or  completing  arbitrage  operations.  By  lending  its
investment  securities,  the Fund attempts to increase its net investment income
through  the  receipt of  interest  on the loan.  Any gain or loss in the market
price of the  securities  loaned  that might  occur  during the term of the loan
would belong to the Fund. The Fund may lend its investment securities so long as
the terms, structure and the aggregate amount of such loans are not inconsistent
with the 1940 Act or the rules and  regulations  or  interpretations  of the SEC
thereunder,  which currently require,  among other things, that (a) the borrower
pledge and maintain with the Fund collateral consisting of liquid,  unencumbered
assets  having  a value at all  times  not less  than  100% of the  value of the
securities loaned, (b) the borrower add to such collateral whenever the price of
the securities loaned rises (i.e., the borrower "marks to the market" on a daily
basis), (c) the loan be made subject to termination by the Fund at any time, and
(d) the Fund  receives  reasonable  interest  on the loan (which may include the
Fund investing any cash collateral in interest bearing short-term  investments),
and  distributions  on the loaned  securities  and any  increase in their market
value. There may be risks of delay in recovery of the securities or even loss of
rights in the collateral should the borrower of the securities fail financially.
However,  loans will be made only to borrowers  selected by the Fund's  delegate
after a  commercially  reasonable  review of relevant  facts and  circumstances,
including the creditworthiness of the borrower.

The Fund may pay negotiated fees in connection with loaned securities,  pursuant
to  written  contracts.  In  addition,  voting  rights  may pass with the loaned
securities,  but if a material event occurs affecting an investment on loan, the
loan must be called and the  securities  voted.  Pursuant to an exemptive  order
granted by the SEC,  cash  collateral  received by the Fund may be invested in a
money market fund managed by the Advisor (or one of its affiliates).



               Please Retain This Supplement for Future Reference


August 13, 2008