-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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<SEC-DOCUMENT>0001075973-07-000001.txt : 20070402
<SEC-HEADER>0001075973-07-000001.hdr.sgml : 20070402
<ACCEPTANCE-DATETIME>20070402110303
ACCESSION NUMBER:		0001075973-07-000001
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20070329
FILED AS OF DATE:		20070402
DATE AS OF CHANGE:		20070402

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			EDGERLEY PAUL B
		CENTRAL INDEX KEY:			0001075973
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-21719
		FILM NUMBER:		07736316

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		9727335405

	MAIL ADDRESS:	
		STREET 1:		17304 PRESTON ROADS
		STREET 2:		SUITE 700
		CITY:			DALLAS
		STATE:			TX
		ZIP:			75252

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			STEEL DYNAMICS INC
		CENTRAL INDEX KEY:			0001022671
		STANDARD INDUSTRIAL CLASSIFICATION:	STEEL WORKS, BLAST FURNACES  ROLLING MILLS (COKE OVENS) [3312]
		IRS NUMBER:				351929476
		STATE OF INCORPORATION:			IN
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		6714 POINTE INVERNESS WAY
		STREET 2:		SUITE 200
		CITY:			FORT WAYNE
		STATE:			IN
		ZIP:			46804
		BUSINESS PHONE:		2604593553

	MAIL ADDRESS:	
		STREET 1:		6714 POINTE INVERNESS WAY
		STREET 2:		SUITE 200
		CITY:			FORT WAYNE
		STATE:			IN
		ZIP:			46804
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2007-03-29</periodOfReport>

    <issuer>
        <issuerCik>0001022671</issuerCik>
        <issuerName>STEEL DYNAMICS INC</issuerName>
        <issuerTradingSymbol>STLD</issuerTradingSymbol>
    </issuer>

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            <rptOwnerName>EDGERLEY PAUL B</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>BAIN CAPITAL</rptOwnerStreet1>
            <rptOwnerStreet2>111 HUNTINGTON AVENUE</rptOwnerStreet2>
            <rptOwnerCity>BOSTON</rptOwnerCity>
            <rptOwnerState>MA</rptOwnerState>
            <rptOwnerZipCode>02199</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
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            <transactionAmounts>
                <transactionShares>
                    <value>1692</value>
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                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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                <transactionShares>
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                <transactionPricePerShare>
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        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
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            </securityTitle>
            <conversionOrExercisePrice>
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            </conversionOrExercisePrice>
            <transactionDate>
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            <transactionCoding>
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                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
                    <value>D</value>
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            <exerciseDate>
                <value>2002-11-21</value>
            </exerciseDate>
            <expirationDate>
                <value>2007-05-21</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
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                <underlyingSecurityShares>
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                <underlyingSecurityShares>
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        </derivativeTransaction>
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                <transactionAcquiredDisposedCode>
                    <value>D</value>
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            <exerciseDate>
                <value>2005-11-21</value>
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            <expirationDate>
                <value>2010-05-21</value>
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            <underlyingSecurity>
                <underlyingSecurityTitle>
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            <ownershipNature>
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        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Number of shares shown and price per share reflect 2:1 stock split effective 11/21/2006.</footnote>
        <footnote id="F2">Acquisition of stock pursuant to exercise of option, granted pursuant to Non-Employee Director Stock Option Plan approved by stockholders, exempt under Rule 16b-6(b).</footnote>
        <footnote id="F3">Exercise of option exempt under Rule 16b-3(e).</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Paul B. Edgerley</signatureName>
        <signatureDate>2007-04-02</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----
