-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 WDtcQ+NalDAzVErWeM3w7i+G49Xo+ErmFM+r/9NVHSRAlfocDv7ALrK6a9YuqFnW
 cStZxtqp2i+/WkjoZZvgsA==

<SEC-DOCUMENT>0000722079-06-000055.txt : 20060817
<SEC-HEADER>0000722079-06-000055.hdr.sgml : 20060817
<ACCEPTANCE-DATETIME>20060817153718
ACCESSION NUMBER:		0000722079-06-000055
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20060731
FILED AS OF DATE:		20060817
DATE AS OF CHANGE:		20060817

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			TERRA INDUSTRIES INC
		CENTRAL INDEX KEY:			0000722079
		STANDARD INDUSTRIAL CLASSIFICATION:	AGRICULTURE CHEMICALS [2870]
		IRS NUMBER:				521145429
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		600 FOURTH ST
		STREET 2:		PO BOX 6000
		CITY:			SIOUX CITY
		STATE:			IA
		ZIP:			51102-6000
		BUSINESS PHONE:		7122771340

	MAIL ADDRESS:	
		STREET 1:		600 FOURTH STREET
		STREET 2:		PO BOX 6000
		CITY:			SIOUX CITY
		STATE:			IA
		ZIP:			51102-6000

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	INSPIRATION RESOURCES CORP
		DATE OF NAME CHANGE:	19920517

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			FISHER DAVID EDWIN
		CENTRAL INDEX KEY:			0001236297

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08520
		FILM NUMBER:		061040796
</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>2006-07-31</periodOfReport>

    <issuer>
        <issuerCik>0000722079</issuerCik>
        <issuerName>TERRA INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>TRA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001236297</rptOwnerCik>
            <rptOwnerName>FISHER DAVID EDWIN</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>600 FOURTH STREET</rptOwnerStreet1>
            <rptOwnerStreet2>P.O. BOX 6000</rptOwnerStreet2>
            <rptOwnerCity>SIOUX CITY</rptOwnerCity>
            <rptOwnerState>IA</rptOwnerState>
            <rptOwnerZipCode>51102-6000</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2006-07-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>F</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>3000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>7.18</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>37800</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <transactionDate>
                <value>2006-08-16</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>7000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>6.39</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>44800</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This director compensation award consists of 10,000 shares of unrestricted TRA common stock, of which 3,000 shares were forfeited in payment of taxes.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Mark A. Kalafut, Attorney-in-fact</signatureName>
        <signatureDate>2006-08-17</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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