-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 AD1socGf3Wtm+z8n7XUi7UxHktIoTfNnH9nwbUH3kcnYJabMNmQaOtzhzh+A5jcQ
 MOXTPqZDPwXruWMdgMlMfQ==

<SEC-DOCUMENT>0001225201-03-000004.txt : 20030616
<SEC-HEADER>0001225201-03-000004.hdr.sgml : 20030616
<ACCEPTANCE-DATETIME>20030616170427
ACCESSION NUMBER:		0001225201-03-000004
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030613
FILED AS OF DATE:		20030616

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			DOWNING JOHN
		CENTRAL INDEX KEY:			0001232878

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-26251
		FILM NUMBER:		03746041

	MAIL ADDRESS:	
		STREET 1:		310 LITTLETON ROAD
		CITY:			WESTFORD
		STATE:			MA
		ZIP:			01886

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			NETSCOUT SYSTEMS INC
		CENTRAL INDEX KEY:			0001078075
		STANDARD INDUSTRIAL CLASSIFICATION:	SERVICES-COMPUTER INTEGRATED SYSTEMS DESIGN [7373]
		IRS NUMBER:				042837575
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0331

	BUSINESS ADDRESS:	
		STREET 1:		4 TECHNOLOGY PARK DR
		CITY:			WESTFORD
		STATE:			MA
		ZIP:			01886
		BUSINESS PHONE:		9786144000

	MAIL ADDRESS:	
		STREET 1:		4 TECHNOLOGY PARK DRIVE
		CITY:			WESTFORD
		STATE:			MA
		ZIP:			01886
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>

<ownershipDocument>

    <documentType>4</documentType>

    <periodOfReport>2003-06-13</periodOfReport>


    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001078075</issuerCik>
        <issuerName>NETSCOUT SYSTEMS INC</issuerName>
        <issuerTradingSymbol>NTCT</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001232878</rptOwnerCik>
            <rptOwnerName>DOWNING JOHN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>V.P. WW Sales Operations</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeSecurity>
        <securityTitle>
            <value>Employee Stock Option (Right to Buy)</value>
        </securityTitle>
        <conversionOrExercisePrice>
            <value>4.22</value>
        </conversionOrExercisePrice>
        <transactionDate>
            <value>2003-06-13</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>5</transactionFormType>
            <transactionCode>A</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionTimeliness>
            <value>E</value>
        </transactionTimeliness>
        <transactionAmounts>
            <transactionShares>
                <value>100000</value>
            </transactionShares>
            <transactionValue>
                <value>0</value>
                <footnoteId id="F2"/>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <exerciseDate>
            <value>2003-06-13</value>
            <footnoteId id="F1"/>
        </exerciseDate>
        <expirationDate>
            <value>2010-09-25</value>
        </expirationDate>
        <underlyingSecurity>
            <underlyingSecurityTitle>
                <value>Common Stock</value>
            </underlyingSecurityTitle>
            <underlyingSecurityShares>
                <value>100000</value>
            </underlyingSecurityShares>
        </underlyingSecurity>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>140000</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </derivativeSecurity>

    <derivativeSecurity>
        <securityTitle>
            <value>Employee Stock Option (Right to Buy)</value>
        </securityTitle>
        <conversionOrExercisePrice>
            <value>4.22</value>
        </conversionOrExercisePrice>
        <transactionDate>
            <value>2003-06-13</value>
        </transactionDate>
        <transactionCoding>
            <transactionFormType>5</transactionFormType>
            <transactionCode>A</transactionCode>
            <equitySwapInvolved>0</equitySwapInvolved>
        </transactionCoding>
        <transactionTimeliness>
            <value>E</value>
        </transactionTimeliness>
        <transactionAmounts>
            <transactionShares>
                <value>25000</value>
            </transactionShares>
            <transactionValue>
                <value>0</value>
                <footnoteId id="F4"/>
            </transactionValue>
            <transactionAcquiredDisposedCode>
                <value>A</value>
            </transactionAcquiredDisposedCode>
        </transactionAmounts>
        <exerciseDate>
            <value>2003-06-13</value>
            <footnoteId id="F3"/>
        </exerciseDate>
        <expirationDate>
            <value>2010-12-01</value>
        </expirationDate>
        <underlyingSecurity>
            <underlyingSecurityTitle>
                <value>Common Stock</value>
            </underlyingSecurityTitle>
            <underlyingSecurityShares>
                <value>25000</value>
            </underlyingSecurityShares>
        </underlyingSecurity>
        <postTransactionAmounts>
            <sharesOwnedFollowingTransaction>
                <value>165000</value>
            </sharesOwnedFollowingTransaction>
        </postTransactionAmounts>
        <ownershipNature>
            <directOrIndirectOwnership>
                <value>D</value>
            </directOrIndirectOwnership>
        </ownershipNature>
    </derivativeSecurity>

    <footnotes>
        <footnote id="F1">25,000 options are exercisable on 6/13/2003 and 6,250 options become exercisable on 9/13/2003 and every 3 months thereafter.</footnote>
        <footnote id="F2">Price is N/A.</footnote>
        <footnote id="F3">6,250 options are exercisable on 6/13/2003 and 1,562.5 options become exercisable on 9/13/2003 and every 3 months thereafter.</footnote>
        <footnote id="F4">Price is N/A.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>John Downing</signatureName>
        <signatureDate>2003-06-16</signatureDate>
    </ownerSignature>

</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----