Filed Pursuant to Rule 424(b)(3)
                                                    Registration No. 333-75862

Prospectus Supplement No. 4 To
Prospectus Dated February 14, 2002

                          CUBIST PHARMACEUTICALS, INC.

           $165,000,000 5 1/2% CONVERTIBLE SUBORDINATED NOTES DUE 2008
             SHARES OF COMMON STOCK ISSUABLE UPON CONVERSION THEREOF

         This prospectus supplement relates to the resale by the selling
securityholders of Cubist Pharmaceuticals, Inc. 5 1/2% Convertible Subordinated
Notes Due 2008 or shares of Cubist Pharmaceuticals, Inc. common stock issued
upon conversion of the subordinated notes.

         This prospectus supplement should be read in conjunction with the
prospectus dated February 14, 2002 and the prospectus supplements dated March
14, 2002, March 29, 2002 and April 10, 2002, and is not complete without, and
may not be delivered or utilized except in connection with, the prospectus,
including any amendments or supplements thereto.

         The following table supplements the information set forth in the
prospectus under the caption "Selling Securityholders" with respect to the
selling securityholders and the respective principal amount of notes which are
beneficially owned and may be sold by each selling securityholder pursuant to
this prospectus, as amended or supplemented. All information concerning
beneficial ownership has been furnished by the selling securityholders.




                                                         PRINCIPAL AMOUNT
                                                         OF SUBORDINATED
                                                              NOTES          PERCENTAGE OF     NUMBER OF SHARES
                                                        BENEFICIALLY OWNED   SUBORDINATED      OF COMMON STOCK
NAME AND ADDRESS OF BENEFICIAL OWNER                     THAT MAY BE SOLD  NOTES OUTSTANDING   THAT MAY BE SOLD
- ------------------------------------                     ----------------  -----------------   ----------------
                                                                                      
HOURGLASS MASTERFUND LTD.                                    $2,400,000         1.5%                 (1)
527 Madison Avenue, 17th Floor
New York, New York  10022

ZCM ASSET HOLDING COMPANY C/O ZURICH CAPITAL MARKETS            600,000           *                  (1)
527 Madison Avenue, 17th Floor
New York, New York  10022



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

* Less than 1% of the outstanding notes

(1) Consists of a number of indeterminable shares of common stock as may be
issued from time to time upon conversion of the subordinated notes, including
such shares as may be issuable by reason of adjustment of the conversion price
as a result of stock splits, stock dividends and similar anti-dilution
provisions.

         INVESTING IN THE SECURITIES INVOLVES RISKS. SEE "RISK FACTORS"
                     BEGINNING ON PAGE 7 OF THE PROSPECTUS.

                                   -----------

         THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE
SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS
THE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE ACCURACY OR
ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL
OFFENSE.

         THE SECURITIES MAY BE SOLD FROM TIME TO TIME BY THE SELLING
SECURITYHOLDERS OR THEIR DONEES, PLEDGEES, TRANSFEREES AND OTHER SUCCESSORS IN
INTEREST IN ONE OR MORE TRANSACTIONS AT FIXED PRICES, AT MARKET PRICES AT THE
TIME OF SALE, AT VARYING PRICES DETERMINED AT THE TIME OF SALE OR AT NEGOTIATED
PRICES.


              THE DATE OF THIS PROSPECTUS SUPPLEMENT IS MAY 7, 2002