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                                                                EXHIBIT 10.21




                     SIXTH AMENDMENT TO MEDAPHIS CORPORATION
                         NON-QUALIFIED STOCK OPTION PLAN
                       FOR EMPLOYEES OF ACQUIRED COMPANIES



         THIS SIXTH AMENDMENT is made the 7th day of January, 1997 by MEDAPHIS
CORPORATION, a corporation organized and doing business under the laws of the
State of Delaware (the "Company").


                               W I T N E S S E T H


         WHEREAS, the Company has previously adopted the Medaphis Corporation
Non-Qualified Stock Option Plan for Employees of Acquired Companies (the
"Plan"); and

         WHEREAS, the Board of Directors of the Company has approved an increase
in the number of shares reserved for issuance pursuant to the Plan to 6,515,000
shares from 5,015,000 shares.

         NOW, THEREFORE, Section 3 of the Plan is hereby amended by deleting
Section 3 of the Plan in its entirety and replacing it with the following:

                                   "Section 3

                         SHARES RESERVED UNDER THE PLAN

         There shall be 6,515,000 shares of Stock reserved for issuance under
         this Plan, and such shares of Stock shall be reserved to the extent
         that the Company deems appropriate from authorized but unissued shares
         of Stock and from shares of Stock which have been repurchased by the
         Company. Furthermore, any shares of Stock subject to an Option that
         remain unissued after the cancellation or expiration of such Option
         thereafter shall again become available for use under this Plan."

         FURTHER, except as specifically amended by this Sixth Amendment, the
Plan shall remain in full force and effect as prior to this Sixth Amendment.
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         IN WITNESS WHEREOF, the Company has caused this Sixth Amendment to be
executed on the day and year first above written.



                                    MEDAPHIS CORPORATION



                                    By: /s/ Michael R. Cote
                                       -----------------------------------------
                                    Title:  Senior Vice President - Finance,
                                            Chief Financial Officer and 
                                            Assistant Secretary


ATTEST:

By: /s/ William R. Spalding
   ---------------------------------
Title:  Senior Vice President,
General Counsel and Secretary


         [CORPORATE SEAL]

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