Washington, DC 20549


                                    FORM 8-K

                                 CURRENT REPORT
                     Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934

       Date of report (Date of earliest event reported) September 15, 2004

                             NetScout Systems, Inc.
               (Exact Name of Registrant as Specified in Charter)

                 (State or Other Jurisdiction of Incorporation)

           0000-26251                                     04-2837575
    (Commission File Number)                   (IRS Employer Identification No.)

310 Littleton Road, Westford, Massachusetts                           01886
 (Address of Principal Executive Offices)                           (Zip Code)

                                 (978) 614-4000
              (Registrant's Telephone Number, Including Area Code)

                                 Not Applicable
          (Former Name or Former Address, If Changed Since Last Report)

      Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions (see General Instruction A.2. below):

      |_| Written communications pursuant to Rule 425 under the Securities Act
(17 CFR 230.425)

      |_| Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17
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      |_| Pre-commencement communications pursuant to Rule 14d-2(b) under the
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      |_| Pre-commencement communications pursuant to Rule 13e-4(c) under the
Exchange Act (17 CFR 240.13e-4(c))


                             Section 8--Other Events

Item 8.01. Other Events.

      Following discussions between NetScout Systems, Inc. ("NetScout") and
Cisco Systems, Inc. ("Cisco") regarding NetScout's plan to terminate support for
its legacy product, Real Time Monitor 1.4, Cisco announced its intention to
discontinue reselling Real Time Monitor as of November 30, 2004. The
announcement was contained in a letter dated September 15, 2004, notifying
NetScout of the non-renewal of the Private Label Agreement dated October 17,
1995, as amended, and the Project Development and License Agreement dated July
13, 1994, as amended, by and between NetScout and Cisco (the "Agreements").
Pursuant to the foregoing and the terms of the Agreements, the Agreements will
terminate on June 1, 2005. NetScout will continue to recognize license and
royalty revenue based upon reported product shipments by Cisco, with the final
product shipments report expected in the fourth quarter of fiscal year 2005. For
fiscal year 2004, license and royalty related to Cisco represented $1.8 million,
or 2%, of total revenue. NetScout does not expect a material impact from Cisco's
non-renewal of the Agreements, as it will be offering Cisco Real Time Monitor
1.4 customers a purchase option to upgrade to nGenius(R) Performance Manager

      Forward-looking statements in this report are made pursuant to the safe
harbor provisions of Section 21E of the Securities Exchange Act of 1934.
Investors are cautioned that statements in this report, which are not strictly
historical statements, including the plans, objectives and future financial
performance of NetScout, constitute forward-looking statements that involve
risks and uncertainties. Actual results could differ materially from the
forward-looking statements. NetScout assumes no obligation to update any
forward-looking information contained in this report or with respect to the
announcements described herein.



      Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                   NETSCOUT SYSTEMS, INC.

September 21, 2004

                                   By: /s/ David P. Sommers
                                       David P. Sommers
                                       Chief Financial Officer and
                                       Senior Vice President, General Operations