<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-03-31</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000097745</issuerCik>
        <issuerName>THERMO FISHER SCIENTIFIC INC.</issuerName>
        <issuerTradingSymbol>TMO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001190290</rptOwnerCik>
            <rptOwnerName>ULLIAN ELAINE</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>81 WYMAN STREET</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX 9046</rptOwnerStreet2>
            <rptOwnerCity>WALTHAM</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>024549046</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2007-03-31</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>393.4</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F2"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F2"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F2"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>393.40</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1037.53</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Convertible into Common Stock on a 1-for-1 basis.</footnote>
        <footnote id="F2">Represents stock units credited to the Reporting Person's account as of March 31, 2007, at a price of $46.39 per unit pursuant to the Issuer's Deferred Compensation Plan for Directors (the 'Plan').  Director's fees and retainers are deferred quarterly under the Plan as Common Stock units based on the average of the opening and closing price of the stock as of the quarter end.  The shares are distributable as stock upon cessation of director service (for any reason) or a change of control.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>By: Barbara J. Lucas, Attorney-in-Fact for Elaine S. Ullian</signatureName>
        <signatureDate>2007-04-03</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2007-03-31
0
0000097745
THERMO FISHER SCIENTIFIC INC.
TMO
0001190290
ULLIAN ELAINE
81 WYMAN STREET
P.O. BOX 9046
WALTHAM
MA
024549046
1
0
0
0
Phantom Stock Units
2007-03-31
4
A
0
393.4
A
Common Stock
393.40
1037.53
D
Convertible into Common Stock on a 1-for-1 basis.
Represents stock units credited to the Reporting Person's account as of March 31, 2007, at a price of $46.39 per unit pursuant to the Issuer's Deferred Compensation Plan for Directors (the 'Plan').  Director's fees and retainers are deferred quarterly under the Plan as Common Stock units based on the average of the opening and closing price of the stock as of the quarter end.  The shares are distributable as stock upon cessation of director service (for any reason) or a change of control.
By: Barbara J. Lucas, Attorney-in-Fact for Elaine S. Ullian
2007-04-03