<PAGE>
Prospectus Supplement Filed Pursuant to Rule 424(b)(3)
(To Prospectus Dated June 11, 1999) Registration No. 333-78909
$850,000,000
Citrix Systems, Inc.
Zero Coupon Convertible Subordinated Debentures Due 2019
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This prospectus supplement relates to the resale by the holders of our Zero
Coupon Convertible Subordinated Debentures Due 2019 and the shares our common
stock, $.001 par value per share, issuable upon the conversion of the
debentures.
This prospectus supplement should be read in conjunction with, and may not
be delivered or utilized without, the prospectus dated June 11, 1999. The terms
of the debentures are set forth in the prospectus.
The information in the table appearing under the heading "Selling
Securityholders" in the prospectus is amended by adding the information below
with respect to persons not previously listed in the prospectus and by
superceding the information with respect to persons previously listed
in the prospectus that are listed below.
<TABLE>
<CAPTION>
Principal Amount
at Maturity of
Debentures Number of
Beneficially Percentage of Conversion
Owned That Debentures Shares That
Name May Be Sold Outstanding May Be Sold
---- ----------- ----------- -----------
<S> <C> <C> <C>
Highbridge International LLC $19,800,000 2.33% 139,205
Allstate Insurance Company $ 6,500,000 0.76% 45,698
Delta Airlines Master Trust $ 5,005,000 0.59% 35,188
State Employees' Retirement $ 4,230,000 0.50% 29,739
Fund of the State of
Delaware
Chrysler Corporation Master $12,005,000 1.41% 84,402
Retirement Trust
Raytheon Company Master $ 6,185,000 0.73% 43,484
Pension Trust
Motion Picture Industry $ 1,440,000 0.17% 10,124
Health Plan--Active
Member Fund
Motion Picture Industry $ 720,000 0.08% 5,062
Health Plan--Retiree
Member Fund
Chase Manhattan NA as $18,865,000 2.22% 132,632
Trustee for IBM
Retirement Plan dated
12/18/45
Bankers Trust as Trustee $12,470,000 1.47% 87,671
for Chrysler Corp.
Emp. #1 Pension Plan
dated 4/1/89
State Street Bank as $ 6,615,000 0.78% 46,507
Custodian for GE
Pension Trust
Franklin & Marshall $ 960,000 0.11% 6,749
College
Penn Treaty Network $ 840,000 0.10% 5,905
America Insurance Co.
Ritchie Capital $ 5,000,000 0.59% 35,153
Investments Ltd.
RAM Capital LLC $ 5,000,000 0.59% 35,153
Any other holder of $370,705,000 43.61% 2,606,298
Debentures or future
transferee from any
such holder
</TABLE>
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The date of this prospectus supplement is June 25, 1999.
