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                                                                    EXHIBIT 10-S

                          FIRST AMENDMENT TO AGREEMENT


      This First Amendment (the "Amendment") is made and entered into effective
as of June 6, 2002 by and between Zila, Inc., a Delaware corporation ("Zila"),
and Douglas, Curtis & Allyn, LLC, a California limited liability company, and
amends the Letter Agreement (the "Agreement") between Zila and DCA, dated March
15, 2001. All capitalized terms in this Amendment shall have the same meanings
as such terms have in the Agreement.

                                    RECITALS

      WHEREAS, Zila and DCA desire to amend the Agreement in accordance with the
terms set forth in this Amendment;

      NOW THEREFORE, in consideration of the foregoing and of the mutual
promises and conditions set forth, the parties agree as follows:


                                    AGREEMENT

      1.    The following Paragraph is hereby added to the Agreement:

            Zila shall pay DCA a Success Fee equal to the following in
      connection with the Transactions indicated below:

            (a)   In regards to the sale of the Zila Dental Supply ("ZDS") full
      service business to Henry Schein, Inc., Zila shall pay DCA a fee of
      $89,489;

            (b)   In regards to the sale of the ZDS mail order business to
      PracticeWares, Inc., Zila will pay DCA a fee of $97,400 upon closing of
      the Transaction; and

            (c)   In regards to The Trylon Corporation, Zila will pay DCA a fee
      of, (i) One half of one percent (.5%) of the value of the Zila shares
      issued to The Trylon Corporation. The payment will be based upon the value
      of the Zila shares issued to Trylon in connection with the Transaction and
      Zila will pay DCA upon completion of the appraisal of the shares by Zila;
      (ii) one half of one percent (.5%) of the value of Zila shares to be
      issued under certain circumstances to Trylon in the future; (such fees to
      be paid within 30 days of such shares' issuances, and (iii) one half of
      one percent (.5%) of any royalty Trylon earns in connection with its
      agreement with Zila, which amount Zila will pay DCA quarterly, as Trylon
      earns the royalty. DCA shall have reasonable audit rights to validate the
      accuracy of such royalty payments.

      2.    Effective Date. This Amendment shall become effective on the date
written above upon the signature of each of the parties to this Agreement.

      3.    Counterparts. This Amendment may be executed in any number of
counterparts, each of which when so executed and delivered will be an original,
but all of which together


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constitute one and the same instrument. For purposes of this Amendment,
facsimile copies of original signatures will be deemed an original signature.

      4.    One Agreement. The Agreement shall be deemed amended to the extent
set forth in this Amendment. The Agreement, as amended by the Amendment, shall
constitute one agreement. All other terms and provisions of the Agreement shall
remain in full force and effect. If there is any inconsistency with the terms of
the Agreement and the Amendment, the terms of the Amendment shall govern over
the Agreement. This Amendment is intended to be a final expression of the
parties' agreement to amend the Agreement and is intended to be a complete and
exclusive statement of their agreement and understanding with respect to such
amendment.

      5.    Severability. If any provision of this Amendment is invalid under
any applicable law, such invalidity shall not affect any other provision of this
Amendment that can be given effect without the invalid provision.

      6.    Documentation. The parties agree to cooperate fully and to execute
any and all supplementary documents and pleadings and to take all additional
actions that may be necessary or appropriate to give full force and effect to
this Amendment and that are not inconsistent with its terms.

      7.    Binding Effect. This Amendment is binding upon and shall enure to
the benefit of the parties hereto and their respective heirs, administrators,
executors, representatives, successors, receivers, trustees and assigns.

      8.    Warranty of Capacity to Sign. Each person executing this Amendment
represents and warrants that he or she is the duly authorized representative of
the party for which he or she acts and is fully and legally empowered to execute
and deliver this document on behalf of the party for which he or she acts.






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            IN WITNESS WHEREOF, this Amendment has been entered into as of the
day and year first above written.

                                    COMPANY:

                                    ZILA, INC.,
                                    a Delaware corporation


                                    s/s Bradley C. Anderson
                                    ------------------------------------------
                                    By:  Bradley C. Anderson.
                                    Its: Treasurer and Chief Financial Officer


                                    DOUGLAS, CURTIS & ALLYN, LLC., a California
                                    limited liability company


                                    s/s Curtis M. Rocca
                                    -----------------------------------------
                                    By:  Curtis M. Rocca
                                    Its: Chief Executive Officer






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