<PAGE>
 
This amendment contains a corrected Exhibit 13 of Item 14 of the 1997 Form 10k. 
The original included typographical errors that occurred during the EDGARization
process.  The corrections for these errors are as follows:
<TABLE> 
<S>                                 <C> 
Item 14, Exhibit 13,  cover, page 3 - 1995, 1996 and 1997 annual growth should be --, 34.2% and 40.6%,
                                      respectively.
Item 14, Exhibit 13, page 1         - Employees should more than 575 in the U.S. and U.K.
Item 14, Exhibit 13, page 14        - The Company paid approximately $66.8 million ((Pounds) 40.0
                                      million) for the facility plus an additional payment for certain working
                                      capital of approximately $1.7 million ((Pound) 1.0 million).
Item 14, Exhibit 13, page 19        - 1996 and 1997 Other Assets should be - and 3,591, respectively.
Item 14, Exhibit 13, page 19        - 1997 Accumulated Deficit should be (11,411).
Item 14, Exhibit 13, page 24        - The Company paid approximately $66.8 million ((Pounds) 40.0
                                      million) for the facility plus an additional payment for certain working
                                      capital of approximately $1.7 million ((Pound) 1.0 million).
Item 14, Exhibit 13, page 29        - Interest costs capitalized in 1997 were $150,000.
</TABLE> 
<PAGE>
 
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                                 UNITED STATES
                      SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, DC 20549
 
                               ----------------
 
                                   FORM 10-K/A
                                AMENDMENT NO. 1
 
                               ----------------
 
             ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                        SECURITIES EXCHANGE ACT OF 1934
 
                  FOR THE FISCAL YEAR ENDED DECEMBER 31, 1997
 
                          COMMISSION FILE NO. 0-27698
 
                                  CHIREX INC.
            (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
            DELAWARE                                  04-3296309
 (STATE OR OTHER JURISDICTION OF          (IRS EMPLOYER IDENTIFICATION NUMBER)
 INCORPORATION OR ORGANIZATION)

    300 ATLANTIC STREET, SUITE 402
        STAMFORD, CONNECTICUT                           06901
 (ADDRESS OF PRINCIPLE EXECUTIVE OFFICE)              (ZIP CODE)
                                        
 
                                (203) 351-2300
             (REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE)
 
    TITLE OF EACH CLASS SECURITIES
 REGISTERED PURSUANT TO SECTION 12(g)
    OF THE SECURITIES EXCHANGE ACT                  NAME OF EXCHANGE
                OF 1934                            ON WHICH REGISTERED
   ___________________________              __________________________________
     COMMON STOCK, $.01 PAR VALUE          THE NASDAQ STOCK MARKET'S NATIONAL
                                                         MARKET
 
SECURITIES REGISTERED PURSUANT TO SECTION 12(b) OF THE SECURITIES EXCHANGE ACT
                                OF 1934: NONE.
 
  Indicate by check mark whether the registrant: (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to
such filing requirements for the past 90 days. Yes [X] No [_]
 
  Indicate by check mark if disclosure of delinquent filers pursuant to Item
405 of Regulation S-K is not contained herein, and will not be contained, to
the best of the registrant's knowledge, in definitive proxy or information
statements incorporated by reference in Part III of this Form 10-K or any
amendment to this Form 10-K [X]
 
  The aggregate market value of the voting stock held by non-affiliates of the
registrant was approximately $197,632,965 as of March 4, 1998.
 
                   APPLICABLE ONLY TO CORPORATE REGISTRANTS
 
  As of March 4, 1998 there were 11,798,983 shares outstanding (excluding as
of such date 1,491,295 shares of common stock issuable upon exercise of
options with a weighted average price of $10.78 per share).
 
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<PAGE>
 
                                  SIGNATURES
 
  Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, as amended, the Registrant has duly caused this Annual
Report on Form 10-K to be signed on its behalf by the undersigned, thereunto
duly authorized, in the Town of Stamford, Connecticut on this 13th day of
March, 1998.
 
                                          CHIREX INC.
 
                                                     /s/ Alan R. Clark
                                          By __________________________________
                                             Alan R. Clark, Chairman and Chief
                                                     Executive Officer
 
  Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, as amended, this Annual Report on Form 10-K has been
signed below by the following persons in the capacities indicated below on
this 13th day of March, 1998.
 
              SIGNATURE                        TITLE
 
        /s/ Alan R. Clark              Chairman of the Board of Directors and
-------------------------------------   Chief Executive Officer (Principal
            Alan R. Clark               Executive Officer)
 
     /s/ Michael A. Griffith           Chief Financial Officer, Secretary and
-------------------------------------   Director (Principal Financial and
         Michael A. Griffith            Accounting Officer)
 
        /s/ Eric Jacobsen              Director
-------------------------------------
          Eric A. Jacobsen
 
         /s/ Dirk Detert               Director
-------------------------------------
             Dirk Detert
 
    /s/ Elizabeth M. Greetham          Director
-------------------------------------
        Elizabeth M. Greetham
 
       /s/ W. Dieter Zander            Director
-------------------------------------
          W. Dieter Zander
 
-------------------------------------
                 SM
 
 
                                      20