FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * SOMMERS DAVID P   2. Issuer Name and Ticker or Trading Symbol NETSCOUT SYSTEMS INC [NTCT] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) CFO & VP General Operations (Last) (First) (Middle) 310 LITTLETON ROAD 3. Date of Earliest Transaction (Month/Day/Year) 01/26/2010 (Street) WESTFORD, MA 01886 4. If Amendment, Date Original Filed(Month/Day/Year) 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 01/26/2010   M(1)   4,757 A (1) (2) 116,659 (8) D   Common Stock 01/26/2010   F(3)   1,806 D $ 14.66 (4) 114,853 (8) D   Common Stock 01/26/2010   M(5)   10,000 A (5) $ 4.22 124,853 (8) D   Common Stock 01/26/2010   S(5)   10,000 D (5) $ 14.619 (6) 114,853 (8) D   Common Stock 01/27/2010   M(5)   10,000 A (5) $ 4.22 124,853 (8) D   Common Stock 01/27/2010   S(5)   10,000 D (5) $ 14.3508 (7) 114,853 (8) D

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Restricted Stock Unit

(2)

01/26/2010

M(1)

4,757

01/26/2010

(9)

Common Stock

4,757

(2)

52,500

D

Employee Stock Options (Right to Buy)

$ 4.22

01/26/2010

M(5)

10,000

(10)

04/25/2010

Common Stock

10,000

$ 0

50,000

D

Employee Stock Options (Right to Buy)

$ 4.22

01/27/2010

M(5)

10,000

(10)

04/25/2010

Common Stock

10,000

$ 0

40,000

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
SOMMERS DAVID P 310 LITTLETON ROAD WESTFORD, MA 01886			CFO & VP General Operations

Signatures

/s/ David P. Sommers		01/28/2010
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	The shares of Common Stock were acquired upon the vesting of certain Restricted Stock Units previously granted to the reporting person.
(2)	Price is N/A.
(3)	The shares of Common Stock were withheld to satisfy the reporting person's tax withholding obligation upon the vesting of restricted stock units.
(4)	Represents the opening price of the Company's Common Stock on the date such grant vested, which was January 24, 2010. Because such date occurred during the Company's blackout period, such shares were not actually issued until the Company's blackout period ended, which was January 26, 2010.
(5)	Option was exercised and related Common stock was sold pursuant to a 10b5-1 plan.
(6)	The shares sold on this date were sold in multiple transactions. This price is the weighted average sales price per share; the actual sales price per share ranged from $14.48 to $14.78.
(7)	The shares sold on this date were sold in multiple transactions. This price is the weighted average sales price per share; the actual sales price per share ranged from $14.23 to $14.45.
(8)	2,500 of these shares are held by a trust in which the reporting person has a pecuniary interest.
(9)	Date is N/A.
(10)	The initial portion of the option grant initially became exercisable on June 13, 2004 and the remainder vested in equal quarterly installments thereafter.

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