<PAGE>
 
                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                                  FORM 10-K/A
                                
                                AMENDMENT NO. 4
                                                    

X   ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT
    OF 1934

                   FOR THE FISCAL YEAR ENDED DECEMBER 31, 1996

    TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE
    ACT OF 1934

        FOR THE TRANSITION PERIOD FROM _______________ TO _______________

                         Commission file number 0-19749


                              CHEMTRAK INCORPORATED
             (Exact name of Registrant as specified in its charter)

DELAWARE                                                              77-0295388
(State or other jurisdiction of                (IRS Employer Identification No.)
incorporation or organization)

929 EAST ARQUES AVENUE, SUNNYVALE, CA                                      94086
(Address of principal executive offices)                              (zip code)

       REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE: (408) 773-8156

Securities registered pursuant to Section 12(b) of the Act:  NONE

Securities registered pursuant to Section 12(g) of the Act:  COMMON STOCK, $.001
                                                             PAR VALUE
<PAGE>
 
                                   SIGNATURES

     Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the Company has duly caused this amendment to its report
on Form 10-K for the year ended December 31, 1996 to be signed on its behalf by
the undersigned, thereunto duly authorized on the 21st day of May, 1998.


                                       CHEMTRAK INCORPORATED

                                       By:   /s/  Donald V. Fluken
                                          ---------------------------------
                                                  Donald V. Fluken
                                               Vice President, Finance
                                         Chief Financial Officer and Secretary

     Pursuant to the requirements of the Securities Exchange Act of 1934, this
report has been signed below by the following persons on behalf of the Company
and in the capacities and on the dates indicated.

<TABLE>     
<CAPTION>
            Signature                         Title                         Date
            ---------                         -----                         ----
<S>                                <C>                                  <C>
 /s/ Prithipal Singh, Ph.D.  
-----------------------------          Chairman of the Board            May 20, 1998
     Prithipal Singh, Ph.D.


 /s/ Edward F. Covell                President, Chief Executive
-----------------------------           Officer and Director            May 21, 1998
     Edward F. Covell              (Principal executive officer)

                                      Vice President Finance,
 /s/ Donald V. Fluken               Chief Financial Officer and         May 21, 1998
-----------------------------      Secretary (Principal financial
     Donald V. Fluken                 and accounting officer)

 /s/ Malcolm Jozoff*
-----------------------------                 Director                  May 20, 1998
     Malcolm Jozoff

 /s/ Robert P. Kiley*
-----------------------------                 Director                  May 20, 1998
     Robert P. Kiley

 /s/ David Rubinstein*
-----------------------------                 Director
     David Rubinstein

 /s/ Gordon W. Russell*
-----------------------------                 Director                  May 20, 1998
     Gordon W. Russell


*By:  /s/ Prithipal Singh, Ph.D.       Vice President Finance,
--------------------------------       Chief Financial Officer          May 20, 1998
          Prithipal Singh, Ph.D.            and Secretary

</TABLE>      
<PAGE>
 
                                    PART IV

Item 14. Exhibits, Financial Statement Schedules, and Reports on Form 8-K.

(c)
         10.36**     Distribution Agreement between ChemTrak and Helena 
                     Laboratories (Canada) Ltd. dated April 25, 1996.

         10.37       Agreement between ChemTrak and Organon Teknika B.V., dated 
                     December 1, 1996.

         10.38       Development and Distribution Agreement between ChemTrak and
                     Selfcare, Inc., dated December 31, 1996.

______________
**  Confidential treatment has been requested for portions of this document.


<PAGE>
 
                               INDEX TO EXHIBITS

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

10.36**         Distribution Agreement between ChemTrak and Helena Laboratories 
                (Canada) Ltd. dated April 25, 1996.

10.37           Agreement between ChemTrak and Organon Teknika B.V., dated 
                December 1, 1996.

10.38           Development and Distribution Agreement between ChemTrak and 
                Selfcare, Inc., dated December 31, 1996.

_____________
** Confidential treatment has been requested for portions of this document.