<SEC-DOCUMENT>0001127602-15-029212.txt : 20151019
<SEC-HEADER>0001127602-15-029212.hdr.sgml : 20151019
<ACCEPTANCE-DATETIME>20151019104844
ACCESSION NUMBER:		0001127602-15-029212
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20151015
FILED AS OF DATE:		20151019
DATE AS OF CHANGE:		20151019

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			GSI GROUP INC
		CENTRAL INDEX KEY:			0001076930
		STANDARD INDUSTRIAL CLASSIFICATION:	MISCELLANEOUS ELECTRICAL MACHINERY, EQUIPMENT & SUPPLIES [3690]
		IRS NUMBER:				980110412
		STATE OF INCORPORATION:			A3
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		125 MIDDLESEX TURNPIKE
		STREET 2:		.
		CITY:			BEDFORD
		STATE:			MA
		ZIP:			01730
		BUSINESS PHONE:		781-266-5618

	MAIL ADDRESS:	
		STREET 1:		125 MIDDLESEX TURNPIKE
		STREET 2:		.
		CITY:			BEDFORD
		STATE:			MA
		ZIP:			01730

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	GSI LUMONICS INC
		DATE OF NAME CHANGE:	19990401

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	GSI LUMONICS
		DATE OF NAME CHANGE:	19990331

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	LUMONICS INC
		DATE OF NAME CHANGE:	19990115

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Glastra Matthijs
		CENTRAL INDEX KEY:			0001561438

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35083
		FILM NUMBER:		151163287

	MAIL ADDRESS:	
		STREET 1:		C/O GSI GROUP CORPORATION
		STREET 2:		125 MIDDLESEX TURNPIKE
		CITY:			BEDFORD
		STATE:			MA
		ZIP:			01730
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2015-10-15</periodOfReport>

    <issuer>
        <issuerCik>0001076930</issuerCik>
        <issuerName>GSI GROUP INC</issuerName>
        <issuerTradingSymbol>GSIG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001561438</rptOwnerCik>
            <rptOwnerName>Glastra Matthijs</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O GSI GROUP CORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>125 MIDDLESEX TURNPIKE</rptOwnerStreet2>
            <rptOwnerCity>BEDFORD</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>01730</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>Chief Operating Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-10-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>75000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>13.90</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>84204</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2015-10-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>32346</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>13.90</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>51858</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2015-10-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>75000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>75000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Each Restricted Stock Unit represents the right to receive one GSI Group Inc. common share upon vesting of such Restricted Stock Unit.</footnote>
        <footnote id="F2">The Restricted Stock Units reported on this Form 4 vest on October 15, 2015.</footnote>
    </footnotes>

    <remarks>Power of Attorney on file</remarks>

    <ownerSignature>
        <signatureName>/s/ Joanna Tow, Attorney-In-Fact</signatureName>
        <signatureDate>2015-10-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>doc1.txt
<DESCRIPTION>POWER OF ATTORNEY (PUBLIC): MGLASTRAPOA
<TEXT>
POWER OF ATTORNEY

Know all by these presents that the undersigned hereby constitutes and
appoints Robert Buckley, Timothy Spinella and Joanna Tow as his true
and lawful attorneys-in-fact to:

(1)	execute for and on behalf of the undersigned Forms 3, 4 and 5
in accordance with Section 16(a) of the Securities Exchange Act of
1934, as amended, and the rules thereunder, for and in relation to
any and all reportable transactions in the securities of
GSI Group, Inc.;

(2)	do and perform any and all acts for and on behalf of the
undersigned which may be necessary or desirable to complete the
execution of any such Form 3, 4 and 5 and timely filing of such forms
with the United States Securities and Exchange Commission and any
other authority; and

(3)	take any other action of any type whatsoever in connection
with the foregoing which, in the opinion of such attorneys-in-fact,
may be of benefit to, in the best interest of, or legally required
by, the undersigned, it being understood that the documents
executed by such attorneys-in-fact on behalf of the undersigned
pursuant to this Power of Attorney shall be in such form and shall
contain such terms and conditions as such attorneys-in-fact may
approve in their discretion.

The undersigned hereby grants to each attorney-in-fact, individually,
full power and authority to do and perform all and every act and
thing whatsoever requisite, necessary and proper to be done in the
exercise of any of the rights and powers herein granted, as fully to
all intents and purposes as each attorney-in-fact might or could do
if personally present, with full power of substitution or revocation,
hereby ratifying and confirming that each attorney-in-fact, or his
substitute or substitutes, shall lawfully do or cause to be done by
virtue of this power of attorney and the rights and powers herein
granted.  The undersigned acknowledges that the foregoing
attorneys-in-fact, in serving in such capacity at the request of the
undersigned, are not assuming any of the undersigned's
responsibilities to comply with Section 16 of the Securities Exchange
Act of 1934, as amended.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney
to be executed as of this 8th day of January, 2015.


	/s/ Matthijs Glastra
	Signature

	Matthijs Glastra
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
