<PAGE>
Filed pursuant to Rule 424(b)(3)
Registration No. 333-78909
Prospectus Supplement
(To Prospectus Dated June 11, 1999)
$850,000,000
[CITRIX LOGO APPEARS HERE]
Zero Coupon Convertible Subordinated Debentures Due 2019
-----------------
This prospectus supplement relates to the resale by the holders of Citrix
Systems, Inc. Zero Coupon Convertible Subordinated Debentures Due 2019 and the
shares of common stock, $.001 par value per share, issuable upon the conversion
of the debentures.
The prospectus supplement should be read in conjunction with, and may not
be delivered or utilized without, the prospectus dated June 11, 1999, including
any amendments or supplements thereto. 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 or in any
amendments or supplements thereto, and by superceding the information with
respect to persons previously listed in the prospectus or in any amendments or
supplements thereto that are listed below:
<TABLE>
<CAPTION>
Principal Amount at Number of
Maturity of Debentures Percentage of Conversion
Beneficially Owned That Debentures Shares That May
Name May Be Sold Outstanding Be Sold
- ---- ----------- ----------- -------
<S> <C> <C> <C>
CIBC World Markets International $ 2,500,000 0.29% 17,576
Arbitrage Corp.
Any other holder of Debentures or future $90,997,000 10.71% 639,796
transferee from any such holder
</TABLE>
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The Date Of This Prospectus Supplement Is September 8, 1999.
