Room 4561
						March 16, 2006



Mr. David Sommers
General Operations and Chief Financial Officer
Netscout Systems, Inc.
310 Littleton Road
Westford, MA 01886

Re:	Netscout Systems, Inc.
	Form 10-K for Fiscal Year Ended March 31, 2005
	Filed June 6, 2005
	Form 10-Q for Fiscal Quarter Ended December 31, 2005
	Filed February 6, 2006
	Form 8-K Filed January 25, 2006
	File No. 000-26251

Dear Mr. Sommers:

      We have reviewed the above referenced filing and have the
following comments.  Please note that we have limited our review
to
the matters addressed in the comments below.  We may ask you to
provide us with supplemental information so we may better
understand
your disclosure.  Please be as detailed as necessary in your
explanation.  After reviewing this information, we may raise
additional comments.

	Please understand that the purpose of our review process is
to
assist you in your compliance with the applicable disclosure
requirements and to enhance the overall disclosure in your filing.
We look forward to working with you in these respects.  We welcome
any questions you may have about our comments or any other aspect
of
our review.  Feel free to call us at the telephone numbers listed
at
the end of this letter.

Form 10-K for the Fiscal Year Ended March 31, 2005

Notes to Consolidated Financial Statements

Note 12. Income Taxes

1. We note that you do not have any valuation allowance recorded
against your deferred tax assets.  Please explain your basis for
concluding that a valuation allowance was not necessary during the
periods presented.  Describe the nature of the positive and
negative
evidence you considered and explain how that evidence was
weighted.
As part of your response, explain the consideration that was given
to
cumulative losses that appear to have existed in each of the years
presented and the recent volatility in your earnings. Refer to
SFAS
109, paragraphs 20 through 25 and 103.

Form 10-Q for the Fiscal Quarter Ended December 31, 2005

Item 2.  Management`s Discussion and Analysis of Financial
Condition
and Results of Operations

Results of Operations

2. We note that on page 29 and page 33 you disclose adjusted
annual
effective tax rate which excludes the effect of a "discrete income
tax benefit."  This appears to be a non-GAAP measure.  Please tell
us
how you have considered the requirements of Item 10(e)(1) of
Regulation S-K.

Form 8-K Filed January 25, 2006

3. We note that you disclose non-GAAP net income and earnings per
share and it appears that your presentation lacks any information
that addresses the various disclosures required by Item
10(e)(1)(i)(C) and (D) and Question 8 of the Frequently Asked
Questions Regarding the Use of non-GAAP Financial Measures.  For
example, the disclosure does not explain the economic substance
behind management`s decision to use the measures, why you believe
the
measures provide investors with useful information, or why it is
helpful to an investor to segregate each of the items for which
adjustments are made.  Additionally, you do not provide any
discussion regarding the material limitations associated with each
measure or the manner in which management compensates for such
limitations. Note that we believe that detailed disclosures should
be
provided for each adjustment to your GAAP results and each non-
GAAP
measure.  Explain to us why you believe your presentation complies
with Item 100(b) of Regulation G, Item 10(e)(1)(i) and Question 8
of
the FAQ.  Alternatively, revise your presentation to comply with
the
relevant guidance.

4. We note your reference to "adjusted" income from operations and
net income and net profit on "an adjusted basis."  This
information
should be referred to as "non-GAAP" rather than as "adjusted"
throughout your disclosures.  Please revise your Form 8-K to
clearly
indicate the measures are of non-GAAP nature.

	As appropriate, please amend your filing and respond to these
comments within 10 business days or tell us when you will provide
us
with a response.  Please submit all correspondence and
supplemental
materials on EDGAR as required by Rule 101 of Regulation S-T.  You
may wish to provide us with marked copies of any amendment to
expedite our review.  Please furnish a cover letter with any
amendment that keys your responses to our comments and provides
any
requested information.  Detailed cover letters greatly facilitate
our
review.  Please understand that we may have additional comments
after
reviewing any amendment and your responses to our comments.

	 We urge all persons who are responsible for the accuracy and
adequacy of the disclosure in the filing reviewed by the staff to
be
certain that they have provided all information investors require
for
an informed decision.  Since the company and its management are in
possession of all facts relating to a company`s disclosure, they
are
responsible for the accuracy and adequacy of the disclosures they
have made.

	In connection with responding to our comments, please
provide,
in writing, a statement from the company acknowledging that:

* the company is responsible for the adequacy and accuracy of the
disclosure in the filing;

* staff comments or changes to disclosure in response to staff
comments do not foreclose the Commission from taking any action
with
respect to the filing; and

* the company may not assert staff comments as a defense in any
proceeding initiated by the Commission or any person under the
federal securities laws of the United States.

      In addition, please be advised that the Division of
Enforcement
has access to all information you provide to the staff of the
Division of Corporation Finance in our review of your filing or in
response to our comments on your filing.

	You may contact Christine Davis, Staff Accountant, at (202)
551-
3408, Mark Kronforst, Senior Staff Accountant at (202) 551-3451 or
me
at (202) 551-3489 if you have questions regarding these comments.

Sincerely,




      Brad Skinner
							Accounting Branch Chief
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Mr. David Sommers
Netscout Systems, Inc.
March 16, 2006
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