EXHIBIT 10
 
                            Amendment No. 1 to the
                                  May 9, 1997
                 License, Development and Marketing Agreement
               Between Microsoft Corporation and Citrix Systems

This Amendment No. 1 is entered into as of April 17, 1998 (the "Amendment
Effective Date"), by and between Microsoft Corporation ("Microsoft") and Citrix
Systems, Inc. ("Citrix"), to amend the License, Development and Marketing
Agreement, dated May 9, 1997 (the "Agreement").

Provided this Amendment has been properly executed on behalf of the parties by
their duly authorized representatives, the parties agree to modify the Agreement
as follows:

     1.  Introduction and Effect of this Amendment.
         ----------------------------------------- 

          Microsoft and Citrix desire to establish an alternative achievement
          milestone for Citrix which, if met, would enable Citrix to achieve the
          financial benefits outlined in Section 9.2.1.1.  The concept behind
          the alternative provided for in this Amendment is that in the event
          the milestone is achieved, Citrix is accepting pre-defined quarterly
          fees (described in Section 9.7 below) in lieu of the royalties
          provided for in Sections 9.1.2 and 9.2 of the Agreement, in exchange
          for Microsoft's commitment to make commercially reasonable efforts to
          package the Hydrix functionality in its relatively high-volume Windows
          NT Server product.

          This Amendment shall add new Sections 9.7, 8.14 and 8.15 to the
          Agreement.  In addition, Section 10.3(ii) shall be amended to add the
          words "and 9.7" after the words "under Sections 9.1 and 9.2".  All
          provisions of the Agreement not so modified shall remain in full force
          and effect.  All defined terms in the Agreement shall have the same
          meaning in this Amendment unless expressly provided to the contrary.

     2.  The Milestone.
         ------------- 

     9.7  In the event Citrix achieves the milestone defined below in this
          Section 9.7 (the "Milestone"), the provisions of this Section shall
          replace and supersede the provisions of Sections 9.1.2 and 9.2 of the
          Agreement  In the event Citrix does not achieve the Milestone, the
          provisions of Section 9.1.2 and 9.2 shall remain unaltered and in full
          force and effect.

          9.7.1    If Citrix achieves the Milestone, then Microsoft shall pay
                   Citrix (i) Ten Million Dollars ($10,000,000) in recognition
                   of Citrix engineering efforts expended in achieving the
                   Milestone, payable upon release to manufacturing of Hydrix
                   4.0; and (ii) a quarterly payment of Fifteen Million Dollars
                   ($15,000,000) per calendar quarter for six (6) quarters

 
                                      -2-



                 beginning with the first quarter after the release to
                 manufacturing of Hydrix 4.0, payable on the first day of such
                 calendar quarter.

               9.7.1.1  In the event Citrix achieves the Milestone and Microsoft
                        ships Multi-User client device support for any device
                        other than a Windows Client Device following the two and
                        one-half year period described in Section 8.7 but before
                        payment in full of all amounts due under Section 9.7.1,
                        then Citrix, in its sole and absolute discretion, may
                        continue to receive the quarterly payments provided for
                        in Section 9.7.1 or may elect to receive a lump sum
                        payment from Microsoft of all outstanding amounts due
                        under Section 9.7.1, payable in full to Citrix within
                        thirty (30) days from the date of its written demand to
                        Microsoft.

               9.7.1.2  For purposes of this Section 9.7, Citrix shall have
                        achieved the Milestone of (i) the final commercial
                        version of Hydrix 4.0 is released to manufacturing by
                        Microsoft on or before May 15, 1998; or (ii) Closure of
                        all [Confidential Treatment Requested]* is achieved on
                        or before April 30, 1998.

               9.7.1.3  For purposes of this Section 9.7, [Confidential
                        Treatment Requested]* shall mean and include only: (i)
                        those [Confidential Treatment Requested]* listed in
                        Schedule 9.7.1.3 (which are a subset of the Hydrix 4
                        [Confidential Treatment Requested]* database as of March
                        17, 1998), (ii) incomplete correction of the
                        [Confidential Treatment Requested]*, and (iii) any
                        regressions to Hydrix functionality caused by
                        corrections to [Confidential Treatment Requested]*. The
                        set of [Confidential Treatment Requested]* shall not be
                        expanded by the Hdyra Test and Acceptance Document dated
                        March 5, 1998.

               9.7.1.4  For purposes of this Section 9.7, Closure shall occur
                        when, in Microsoft's sole and absolute judgment, the
                        criteria for closure of [Confidential Treatment
                        Requested]* has been met as determined in accordance
                        with Version 1.2 of the Hydra Test and Acceptance
                        Document dated March 5, 1998 or a mutually agreed-upon
                        subsequent version, including passage of all applicable
                        acceptance tests.

* [CONFIDENTIAL TREATMENT REQUESTED] INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.  ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE COMMISSION PURSUANT TO RULE 24b-2 PROMULGATED
UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.

 
                                      -3-

               9.7.1.5  Citrix delivered initial test results to Microsoft on
                        April 7, 1998. Microsoft shall notify Citrix in writing
                        or via electronic mail (with confirmed receipt) no later
                        than April 20, 1998, whether Closure has been achieved.
                        If Microsoft determines Closure has not been achieved,
                        Microsoft's written notice shall identify all
                        deficiencies and Citrix shall have until April 30, 1998,
                        to meet the applicable criteria. If Citrix disagrees
                        with Microsoft's determination of deficiencies, the
                        parties agree to utilize the escalation procedure
                        described in Schedule 9.7.1.5 or a mutually agreed
                        alternative procedure. In all matters relating to
                        achievement of Closure, Microsoft and Citrix shall act
                        in good faith.

          9.7.2    By September 30, 1998, Microsoft will notify Citrix if
                   Microsoft will include the Hydrix functionality in its
                   standard Windows NT Server product, in addition to any other
                   packaging for Hydrix that Microsoft may offer in its sole and
                   absolute discretion. If Microsoft does not elect to make such
                   inclusion, quarterly payments due Citrix will continue per
                   Section 9.7.1 through the quarter ended September 30, 1998,
                   at which time the balance of all outstanding amounts due
                   under Section 9.7.1 shall become payable over the succeeding
                   three (3) quarters, in equal quarterly increments.

     8.14  Microsoft agrees that it will configure the initial release of the
           Windows-Based Terminal ("WBT") Kit so that an OEM may, if it chooses,
           configure the Hydrix client software with or without Microsoft's
           Remote Desktop Protocol ("RDP") installed.  Microsoft also agrees to
           bundle ICA client documentation in the initial release of the WBT Kit
           under the same terms as it bundles ICA client software as set forth
           in Section 8.11 of the Agreement, provided such documentation does
           not exceed the length of the RDP documentation provided by Microsoft
           with the WBT Kit, and meets Microsoft's standards for style and
           quality.

     8.15  Microsoft agrees to use good faith efforts to develop Internet
           commercial use licensing for Hydrix.

 
                                      -4-

     IN WITNESS WHEREOF, the parties have duly authorized their representatives
to make and sign this Amendment No. 1.

CITRIX SYSTEMS, INC.                     MICROSOFT CORPORATION


By: /s/ Edward E. Iacobucci              By: /s/ Paul Maritz           
    -----------------------                  ----------------------   

Name: Edward E. Iacobucci                Name: Paul Maritz
      ---------------------                    --------------------   

Title: Chairman                          Title: Vice President           
       --------------------                     -------------------      

Date: 4/17/98                            Date: 4/17/98              
      ---------------------                    -------------------- 

 
                                      -5-

                               Schedule 9.7.1.3

                      [Confidential Treatment Requested]*



* [CONFIDENTIAL TREATMENT REQUESTED] INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.  ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE COMMISSION PURSUANT TO RULE 24b-2 PROMULGATED
UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.


                               Schedule 9.7.1.5

                      [Confidential Treatment Requested]*


* [CONFIDENTIAL TREATMENT REQUESTED] INDICATES MATERIAL THAT HAS BEEN OMITTED
AND FOR WHICH CONFIDENTIAL TREATMENT HAS BEEN REQUESTED.  ALL SUCH OMITTED
MATERIAL HAS BEEN FILED WITH THE COMMISSION PURSUANT TO RULE 24b-2 PROMULGATED
UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED.