EXHIBIT 10.33



                                   [APPLIED BIOSCIENCE]
                                   [INTERNATIONAL INC.]
                                          [LOGO]





                                   September 14, 1993



      Mr. Stephen L. Waechter
      Chief Financial Officer
      Applied Bioscience International Inc.
      4350 North Fairfax Drive, Suite 300
      Arlington, Virginia 22203

      Dear Steve:

              APPLIED BIOSCIENCE INTERNATIONAL INC. (the "Company")
      considers the establishment and maintenance of a sound and vital
      management to be essential to protecting and enhancing the best
      interests of the Company and its shareholders. In this
      connection, the Company recognizes that, as is the case with many
      publicly held corporations, the possibility of a change in
      control may exist and that such possibility, and the uncertainty
      and questions which it may raise among management may result in
      the departure or distraction of management personnel to the
      detriment of the Company and its shareholders. Accordingly, the
      Company's Board of Directors has determined that should the
      Company become subject to any proposed or threatened change in
      the control of the Company, it is imperative that the Company and
      the Board of Directors be able to rely upon you to remain in your
      position and to provide advice, if requested, as to the best
      interests of the Company.

              In order to induce you to remain in the employ of the
      Company, this letter agreement sets forth the severance benefits
      which the Company agrees will be provided to you in the event
      your employment with the Company is terminated subsequent to a
      "change in control of the Company" (as defined in Section 1
      hereof) under the circumstances described below.

               1.    CHANGE IN CONTROL. No benefits shall be payable
      hereunder unless there shall have been a change in control of the
      Company, as set forth below, and your employment by the Company
      shall thereafter have been terminated in accordance with Section
      3 below. For purposes of this Agreement, a "change in control of
      the Company" shall mean a change in control of a nature that
      would be required to be reported in response to Item 6(e) of
      Schedule 14A of Regulation 14A promulgated under the Securities
      Exchange Act of 1934, as amended ("Exchange Act"); provided that,
      without limitation, such a change in control shall be deemed to

      4350 North Fairfax Drive * Arlington, VA 22203  Tel: (703) 516-2490 
                                                      Fax: (703) 516-2494





      Mr. Stephen L. Waechter
      September 14, 1993
      Page 2

      have occurred if (i) any "person" (as such term is used in
      Sections 13(d) and 14(d)(2) of the Exchange Act) is or becomes
      the beneficial owner, directly or indirectly, of securities of
      the Company representing fifty percent (50%) or more of the
      combined voting power of the Company's then outstanding
      securities; or (ii) during any period of two consecutive years,
      individuals who at the beginning of such period constitute the
      Board of Directors of the Company (the "Board") cease for any
      reason to constitute at least a majority thereof unless the
      election, or the nomination for election by the Company's
      shareholders, of each new director was approved by a vote of at
      lease two-thirds of the directors then still in office who were
      directors at the beginning of the period.

           2.    TERMINATION FOLLOWING CHANGE IN CONTROL.

                        (a) If any of the events described in Section 1 hereof
      constituting a change in control of the Company shall have
      occurred, you shall be entitled to the benefits provided in
      Section 3 hereof if the Company subsequently terminates your
      employment unless (i) such termination is (A) because of your
      death or (B) by the Company for Disability; or (ii) such
      termination is (A) by the Company and occurs more than one (1)
      year subsequent to the date of such change of control or (B) you
      unilaterally terminate your employment after a change in control.

                        (b) "Disability" as used herein means that as a result
      of your incapacity due to physical or mental illness, you shall
      have been absent from your duties with the Company on a full-time
      basis for one hundred eighty (180) consecutive days (or for
      shorter period aggregating not less than one hundred eighty (180)
      days during any period of twelve (12) months).

             3.    COMPENSATION UPON TERMINATION. If, within the first
      year following a change of control, the Company shall terminate
      your employment other than pursuant to the reasons set forth in
      paragraph 2(a) hereof, then the Company shall be obligated to
      continue to pay to you as severance pay, the following amounts:

                        (a) your full base salary together with benefits
      through the one year anniversary of the change of control at the
      rate in effect at the time of your termination;

                        (b) all stock options granted to you under the
      Company's stock option plans prior to such termination shall vest




      Mr. Stephen L. Waechter
      September 14, 1993
      Page 3

      as of the date of such termination and you will have the right,
      for a period of one hundred eighty (180) days following such
      termination, to exercise all such stock options which have not
      expired.

              4.    LAPSE. Should you voluntarily leave employment (other
      than after a change in control as provided in Paragraph 3) this
      Agreement shall lapse and be of no other force and effect and no
      compensation will be payable to you hereunder.

              5.     SUCCESSORS; BINDING AGREEMENT.

                          (a) The Company will require any successor
      (whether direct or indirect, by purchase, merger, consolidation
      or otherwise) to all or substantially all of the business and/or
      assets of the Company, to expressly assume and agree to perform
      this Agreement in the same manner and to the same extent that the
      Company would be required to perform it if no such succession had
      taken place.

                          (b) This Agreement shall inure to the benefit of
      and be enforceable by your personal or legal representatives,
      executors, administrators, successors, heirs, distributees,
      devisees and legatees.

              6.    NOTICE. For the purposes of this Agreement, notices
      and all other communications provided for in the Agreement shall
      be in writing and shall be deemed to have been duly given when
      delivered or mailed by registered mail, return receipt requested,
      postage prepaid, addressed to the respective addresses set forth
      on the first page of this Agreement, provided that all notices to
      the Company shall be directed to the attention of the Chief
      Executive Officer of the Company with a copy of the Secretary of
      the Company, or to such other address as either party may have
      furnished to the other in writing in accordance herewith, except
      that notices of change of address shall be effective only upon
      receipt.

              7.    MISCELLANEOUS. No provisions of this Agreement may be
      modified, waived or discharged unless such waiver, modification
      or discharge is agreed to in writing signed by you and such
      officer as may be specifically designated by the Board of
      Directors of the Company. No waiver by either party hereto at
      any time of any breach by the party hereto of, or compliance
      with, any condition or provision of this Agreement to be



       Mr. Stephen L. Waechter
       September 14, 1993
       Page 4

       performed by such other party shall be deemed a waiver of similar
       or dissimilar provisions or conditions at the same or at any
       prior or subsequent time. No agreement or representations, oral
       or otherwise, express or implied, with respect to the subject
       matter hereof have been made by either party which are not set
       forth expressly in this Agreement. The validity, interpretation,
       construction and performance of this Agreement shall be governed
       by the laws of the State of Delaware.

               8.    VALIDITY. The invalidity or unenforceability of any
       provisions of this Agreement shall not effect the validity or
       enforceability of any other provision of this Agreement, which
       shall remain in full force and effect.

               9.    COUNTERPARTS. This Agreement may be executed in one or
       more counterparts, each of which shall be deemed to be an
       original but all of which together will constitute one and the
       same instrument.

               If this letter correctly sets forth our agreement on the
       subject matter hereof, kindly sign and return to the Company the
       enclosed copy of this letter which will then constitute our
       agreement on this subject.

                                   Sincerely,

                                   APPLIED BIOSCIENCE INTERNATIONAL
                                       INC.

                                   By:  /s/ Grover C. Wrenn
                                        -----------------------
                                        Grover C. Wrenn
                                        Chief Executive Officer

       Agreed to this 16th day of
       September, 1993.

       /s/ Stephen L. Waechter
       ------------------------
       Stephen L. Waechter