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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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<SEC-DOCUMENT>0001250842-10-000017.txt : 20100409
<SEC-HEADER>0001250842-10-000017.hdr.sgml : 20100409
<ACCEPTANCE-DATETIME>20100409165634
ACCESSION NUMBER:		0001250842-10-000017
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20100407
FILED AS OF DATE:		20100409
DATE AS OF CHANGE:		20100409

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			AMY DAVID B
		CENTRAL INDEX KEY:			0001253997

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-26076
		FILM NUMBER:		10743106

	MAIL ADDRESS:	
		STREET 1:		10706 BEAVER DAM RD
		CITY:			COCKEYSVILLE
		STATE:			MD
		ZIP:			21030

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SINCLAIR BROADCAST GROUP INC
		CENTRAL INDEX KEY:			0000912752
		STANDARD INDUSTRIAL CLASSIFICATION:	TELEVISION BROADCASTING STATIONS [4833]
		IRS NUMBER:				521494660
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		10706 BEAVER DAM ROAD
		CITY:			HUNT VALLEY
		STATE:			MD
		ZIP:			21030
		BUSINESS PHONE:		4105681500

	MAIL ADDRESS:	
		STREET 1:		10706 BEAVER DAM ROAD
		CITY:			HUNT VALLEY
		STATE:			MD
		ZIP:			21030
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-04-07</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000912752</issuerCik>
        <issuerName>SINCLAIR BROADCAST GROUP INC</issuerName>
        <issuerTradingSymbol>sbgi</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001253997</rptOwnerCik>
            <rptOwnerName>AMY DAVID B</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>10706 BEAVER DAM RD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>COCKEYSVILLE</rptOwnerCity>
            <rptOwnerState>MD</rptOwnerState>
            <rptOwnerZipCode>21030</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Executive Vice President &amp; CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-04-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1629</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.225</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>87709</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-04-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1599</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>5.075</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>86110</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Common Stock issued as Restricted Stock.  Mr. Amy also owns 36,400 shares of Common Stock in street name, 6560.493327 shares of Common Stock held in a 4901(k) plan and 56,215.2772 shares of Common Stock held by an Employee Stock Purchase Plan.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Lisa A. Olivieri, Esq., on behalf of David B. Amy by Power of Attorney</signatureName>
        <signatureDate>2010-04-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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