SUPPLEMENT TO THE CURRENTLY EFFECTIVE PROSPECTUSES:

                                 -----------------

                          DWS MONEY MARKET PRIME SERIES

                        DWS Cash Investment Trust Class A
                        DWS Cash Investment Trust Class B
                        DWS Cash Investment Trust Class C
                        DWS Cash Investment Trust Class S
                              DWS Money Market Fund

The following information supplements the disclosure in the "Other Policies"
section of the fund's prospectuses:

The fund may also post on the Web site, on a more frequent basis, a percentage
breakdown of the holdings of the fund by type of security.

The following information replaces similar disclosure in the "Policies You
Should Know About -- Transaction Processing" section of the fund's prospectuses:

Transaction Processing.  Orders for the purchase of shares by wire transfer will
normally be effective at the share price next computed after receipt of the wire
transfer of the amount to be  invested.  If a wire  transfer  purchase  order is
received in good form prior to 2:00 p.m.  Eastern time, it will normally receive
the dividend for that day.

Investments by check will be effective on the business day following receipt and
will earn dividends the following business day.

Orders processed through dealers or other financial services firms via Fund/SERV
will be effected at the share price calculated on the trade day (normally the
date the order is received). Purchases processed via Fund/SERV will begin
earning dividends on the day the fund receives the payment (typically the next
business day). For redemptions processed via Fund/SERV, you generally will
receive dividends accrued up to, but not including, the business day that
payment for your shares is made.

March 31, 2008
DMMF-3600
                                                                     [Logo]DWS
                                                                       SCUDDER
                                                           Deutsche Bank Group



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When selling shares, shareholders generally receive dividends up to, but not
including, the business day following the day on which the shares were sold.
Applicable to DWS Cash Investment Trust Class S and DWS Money Market Fund only:
If the fund receives a sell request before 12:00 p.m. Eastern time and the
request calls for proceeds to be sent out by wire, the proceeds will normally be
wired on the same day. However, the shares sold will not earn that day's
dividend.

As noted elsewhere in the prospectus, proceeds of a redemption may be delayed.
The ability to receive "same day" wire redemption proceeds can be affected by a
variety of circumstances including the time that the request is made, the level
of redemption requests and purchase orders and general market conditions.
Requests for same day wire that are received earlier in the day will be given
priority over requests received later in the day in the event that it is
necessary to limit the amount of same day wire redemptions.

The following information replaces similar disclosure in the "Policies You
Should Know About -- Transaction Processing" section of the fund's prospectuses:

The fund is open for business each day the New York Stock Exchange is open.
Normally, the fund calculates its share price once every business day as of the
close of regular trading on the Exchange (typically 4:00 p.m. Eastern time, but
sometimes earlier, as in the case of scheduled half-day trading or unscheduled
suspensions of trading). In the event of scheduled partial day trading or
unscheduled suspensions of trading on the Exchange, the calculation of share
price shall be as of the close of trading on the Exchange and the latest time
for receipt of wire purchase transactions entitled to receive same day dividend
treatment and for receipt of redemption orders for same day wire transfer of
proceeds will be the earlier of (a) the times set forth in the prospectus or (b)
the early closing time of the Exchange. The fund seeks to maintain a stable
$1.00 share price.




March 31, 2008
DMMF-3600

                                      2
<PAGE>



The fund may, but is not required to, accept certain types of purchase and
redemption orders (not including exchanges) on days that the Exchange is closed,
or beyond an Exchange early closing time (referred to as a "Limited Trading
Period") if: (a) the Federal Reserve system is open, (b) the primary trading
markets for the fund's portfolio instruments are open and (c) the Advisor
believes there will be adequate liquidity in the short-term markets. During any
such Limited Trading Period, the fund will only accept purchase orders by wire
and telephone redemption orders with proceeds to be sent by wire, ACH or check
and will not accept orders by any other means. (Automated Telephone Line orders
are not permitted.) If redemption proceeds are requested by ACH or check, the
transmission of the ACH payment or the mailing of the check, as the case may be,
will be delayed by at least one business day in comparison to normal trading
periods. Orders submitted by other means will be processed on the next day that
the Exchange is open. The calculation of share price will be at the time set
forth in the prospectus for normal trading days. Orders must be submitted by the
cut-off times for receipt of wire purchases entitled to that day's dividend and
for receipt of telephone redemption orders for same day wire transfer, which
will be the earlier of: (a) the times set forth in the prospectus for normal
trading days or (b) such earlier times that the fund determines based on the
criteria described above. If redemption proceeds are requested by ACH or check,
orders must be received prior to the calculation of share price. Please call
(877) 237-1131 or visit our Web site at www.dws-scudder.com for additional
information about whether the fund will be open for business on a particular
day. Information concerning the intention of the fund to be open for a Limited
Trading Period will be available at least one business day prior to the
applicable day that the Exchange is closed or is closing early in the case of
scheduled closings and as soon as practical in the case of unscheduled closings.


March 31, 2008
DMMF-3600


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<PAGE>







               Please Retain This Supplement for Future Reference






March 31, 2008
DMMF-3600

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