-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 K5l4S7WGC1cyHg24Aepr4M8wf8svn7DWh2jQetITyoVfCLM1nR3vN9rnFnerq3nU
 KTRadzQX6nq2UNI6fca2CQ==

<SEC-DOCUMENT>0001209191-10-050197.txt : 20101012
<SEC-HEADER>0001209191-10-050197.hdr.sgml : 20101011
<ACCEPTANCE-DATETIME>20101012214130
ACCESSION NUMBER:		0001209191-10-050197
CONFORMED SUBMISSION TYPE:	4/A
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100928
FILED AS OF DATE:		20101012
DATE AS OF CHANGE:		20101012

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Szurek Paul E.
		CENTRAL INDEX KEY:			0001498577

	FILING VALUES:
		FORM TYPE:		4/A
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-34877
		FILM NUMBER:		101120382

	MAIL ADDRESS:	
		STREET 1:		C/O CORESITE REALTY CORPORATION
		STREET 2:		1050 17TH STREET, SUITE 800
		CITY:			DENVER
		STATE:			CO
		ZIP:			80265

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			CoreSite Realty Corp
		CENTRAL INDEX KEY:			0001490892
		STANDARD INDUSTRIAL CLASSIFICATION:	REAL ESTATE INVESTMENT TRUSTS [6798]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		1050 17TH STREET
		STREET 2:		SUITE 800
		CITY:			DENVER
		STATE:			CO
		ZIP:			80265
		BUSINESS PHONE:		(866) 777-2673

	MAIL ADDRESS:	
		STREET 1:		1050 17TH STREET
		STREET 2:		SUITE 800
		CITY:			DENVER
		STATE:			CO
		ZIP:			80265
</SEC-HEADER>
<DOCUMENT>
<TYPE>4/A
<SEQUENCE>1
<FILENAME>c06852_4ax0.xml
<DESCRIPTION>MAIN DOCUMENT DESCRIPTION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2010-09-28</periodOfReport>

    <dateOfOriginalSubmission>2010-09-30</dateOfOriginalSubmission>

    <issuer>
        <issuerCik>0001490892</issuerCik>
        <issuerName>CoreSite Realty Corp</issuerName>
        <issuerTradingSymbol>COR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001498577</rptOwnerCik>
            <rptOwnerName>Szurek Paul E.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>1050 17TH STREET, SUITE 800</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DENVER</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80265</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Director</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-09-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>5000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>16</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>5000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">These were inadvertently omitted shares purchased by the reporting person in the initial public offering.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Erick H. Bromfield, attorney-in-fact</signatureName>
        <signatureDate>2010-10-12</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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