UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON D.C. 20549

                                  ____________


                                    FORM 8-K


                                 CURRENT REPORT
                     Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934


Date of report (Date of earliest event reported): October 19, 2004


                              The Medicines Company
--------------------------------------------------------------------------------
               (Exact Name of Registrant as Specified in Charter)


          Delaware                   000-31191                    04-3324394
-----------------------------     ---------------           --------------------
(State or Other Jurisdiction        (Commission                (IRS Employer
     of Incorporation)              File Number)             Identification No.)


             8 Campus Drive
         Parsippany, New Jersey                                07054
 ------------------------------------------                 ------------
  (Address of Principal Executive Offices)                   (Zip Code)

Registrant's telephone number, including area code: (973) 656-1616


--------------------------------------------------------------------------------
          (Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions (see General Instruction A.2. below):

|_|  Written communications pursuant to Rule 425 under the Securities Act (17
     CFR 230.425)

|_|  Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR
     240.14a-12)

|_|  Pre-commencement communications pursuant to Rule 14d-2(b) under the
     Exchange Act (17 CFR 240.14d-2(b))

|_|  Pre-commencement communications pursuant to Rule 13e-4(c) under the
     Exchange Act (17 CFR 240.13e-4(c))




Item 2.02. Results of Operations and Financial Condition.

     On October 19, 2004, The Medicines Company (the "Company") issued a press
release revising the 2004 financial guidance that the Company had provided in a
press release issued, and on a scheduled conference call held, earlier on
October 19, 2004. The full text of the press release is furnished as Exhibit
99.1 to this Current Report on Form 8-K.

     The information in this Form 8-K (including Exhibit 99.1) shall not be
deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934
(the "Exchange Act") or otherwise subject to the liabilities of that section,
nor shall it be deemed incorporated by reference in any filing under the
Securities Act of 1933 or the Exchange Act, except as expressly set forth by
specific reference in such a filing.

Item 9.01. Financial Statements and Exhibits

(c)  Exhibits

     The following exhibit relating to Item 2.02 shall be deemed to be 
     furnished, and not filed:

     99.1  Press Release entitled "The Medicines Company Clarifies 2004 
           Guidance, Increasing Revenue Forecast" issued by The Medicines 
           Company on October 19, 2004.




                                   SIGNATURES


     Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                             THE MEDICINES COMPANY


Date: October 20, 2004                       By: /s/ Steven H. Koehler
                                                 ---------------------
                                                 Steven H. Koehler
                                                 Senior Vice President and Chief
                                                 Financial Officer



                                  Exhibit Index


Exhibit No.              Description
-----------              -----------

   99.1                  Press release dated October 19, 2004 entitled "The
                         Medicines Company Clarifies 2004 Guidance, Increasing
                         Revenue Forecast"