<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0201</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-08-19</periodOfReport>
    <issuer>
        <issuerCik>0000036315</issuerCik>
        <issuerName>FIRST FINANCIAL CORP /TX/</issuerName>
        <issuerTradingSymbol>FFC</issuerTradingSymbol></issuer><reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001042721</rptOwnerCik>
            <rptOwnerName>MANN DAVID W</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>800 WASHINGTON AVE.</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>WACO</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>76701</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>1</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>1</isTenPercentOwner><isOther>0</isOther><officerTitle>President</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeTable><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-08-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F1"/></transactionCoding><transactionAmounts><transactionShares><value>3</value></transactionShares><transactionPricePerShare><value>0</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>81</value><footnoteId id="F2"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-08-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>P</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>58</value></transactionShares><transactionPricePerShare><value>7.50</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>139</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value/></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-08-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F3"/></transactionCoding><transactionAmounts><transactionShares><value>30743.86</value></transactionShares><transactionPricePerShare><footnoteId id="F3"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>30743.86</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Through MCRLT</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-08-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F4"/></transactionCoding><transactionAmounts><transactionShares><value>282</value></transactionShares><transactionPricePerShare><footnoteId id="F4"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>31025.86</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Through MCRLT</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-08-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F5"/></transactionCoding><transactionAmounts><transactionShares><value>30607.86</value></transactionShares><transactionPricePerShare><footnoteId id="F5"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>30607.86</value><footnoteId id="F6"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Through 1990 Trust's indirect interest in CTBC</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-08-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F7"/></transactionCoding><transactionAmounts><transactionShares><value>31081.86</value></transactionShares><transactionPricePerShare><footnoteId id="F7"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>31081.86</value><footnoteId id="F6"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Through 1990 Trust's indirect interest in MGIC</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-08-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F8"/></transactionCoding><transactionAmounts><transactionShares><value>61689.72</value></transactionShares><transactionPricePerShare><footnoteId id="F8"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>70944.72</value><footnoteId id="F6"/><footnoteId id="F9"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Through 1990 Trust's indirect interest in BIL</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-08-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F10"/></transactionCoding><transactionAmounts><transactionShares><value>9735</value></transactionShares><transactionPricePerShare><footnoteId id="F10"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>102477</value><footnoteId id="F6"/><footnoteId id="F11"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Through interests in FFHL</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-08-19</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>J</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F12"/></transactionCoding><transactionAmounts><transactionShares><value>30025.76</value></transactionShares><transactionPricePerShare><footnoteId id="F12"/></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>102477</value><footnoteId id="F6"/><footnoteId id="F13"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Through interests in FFHL</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeTransaction><securityTitle><value>Common Stock</value></securityTitle><transactionDate><value>2003-08-19</value><footnoteId id="F14"/></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>P</transactionCode><equitySwapInvolved>0</equitySwapInvolved><footnoteId id="F15"/></transactionCoding><transactionAmounts><transactionShares><value>24799.4</value></transactionShares><transactionPricePerShare><value>20.49</value></transactionPricePerShare><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>102477</value><footnoteId id="F6"/><footnoteId id="F16"/></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Through interests in FFHL</value></natureOfOwnership></ownershipNature></nonDerivativeTransaction><nonDerivativeHolding><securityTitle><value>Common Stock</value></securityTitle><postTransactionAmounts><sharesOwnedFollowingTransaction><value>421</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>Through interest in MCRLT</value></natureOfOwnership></ownershipNature></nonDerivativeHolding></nonDerivativeTable><footnotes><footnote id="F1">Distribution to Reporting Person from trust of which he is a beneficiary.  The transactions reported in this report are part of a reorganization and consolidation of the assets owned and controlled by the Reporting Person, certain of his family members and entities owned or controlled by them.  </footnote><footnote id="F2">Includes 78 shares acquired by the Reporting Person as a distribution from Barclay, Inc., a corporation wholly-owned by the Reporting Person.  The 78 shares were previously reported as indirectly held by the Reporting Person through Barclay, Inc.</footnote><footnote id="F3">Change in nature of beneficial ownership.  The Reporting Person contributed the following to MCRLT Group, L.P. (&quot;MCRLT&quot;), a limited partnership of which he is the sole general partner and sole limited partner: (i) his 139  directly owned shares and (ii) his 33% limited partner interest in First Financial Holdings, Ltd. (&quot;FFHL&quot;), which represents an interest in 30,604.86 shares, previously reported as indirectly owned.  The Reporting Person also maintains a .5% general partner interest in FFHL directly and an indirect interest in a .5% general partner interest in FFHL held by FFC Holdings, Inc., a corporation wholly-owned by the David W. Mann 1990 Trust (the &quot;1990 Trust&quot;), of which the Reporting Person is a beneficiary.</footnote><footnote id="F4">Contribution to MCRLT of shares held by trusts for the benefit of the Reporting Person's children.  These 282 shares were previously reported as indirectly held by the Reporting Person through the trusts.</footnote><footnote id="F5">Contribution by a limited partner of 3 shares of the Issuer and a 33% limited partner interest in FFHL to Central Texas Broadcasting Co.(&quot;CTBC&quot;), a limited partnership, of which a wholly-owned subsidiary of the 1990 Trust is the .5% general partner.  </footnote><footnote id="F6">The Reporting Person disclaims beneficial ownership of these shares except to the extent of his pecuniary interest therein.</footnote><footnote id="F7">Contribution by a limited partner of 477 shares of the Issuer and a 33% limited partner interest in FFHL to Mann Group Investment Co. (&quot;MGIC&quot;), a limited partnership, of which a wholly-owned subsidiary of the 1990 Trust is the .01% general partner.  </footnote><footnote id="F8">Contribution by CTBC and MGIC to Bluebonnet Investments, Ltd. (&quot;BIL&quot;), of which a wholly-owned subsidiary of the 1990 Trust is the .5% general partner, of an aggregate of 480 shares of the Issuer and a 66% limited partnership interests in FFHL (representing 61209.72 shares of the Issuer).  </footnote><footnote id="F9">Represents contributions by CTBC and MGIC and 9,255 shares of the Issuer previously owned by BIL.</footnote><footnote id="F10">Contribution by BIL, as a limited partner, to FFHL of shares of the Issuer.  </footnote><footnote id="F11">Represents shares of the Issuer contributed by BIL and 92,742 shares of the Issuer previously owned by FFHL.</footnote><footnote id="F12">Distribution from BIL to MCRLT, a limited partner, of a 29.3% limited partner interest in FFHL.  MCRLT, which previously held a 33% limited partner interest in FFHL, now owns a 62.3% limited partner interest in FFHL.</footnote><footnote id="F13">The Reporting Person's indirect interest in these shares includes a 62.3% limited partner interest in FFHL, a .5% general partner interest in FFHL, and an interest (through the 1990 Trust) in FFC Holdings, Inc., the other .5% general partner of FFHL.</footnote><footnote id="F14">Date of agreement to purchase.</footnote><footnote id="F15">Purchase of a 24.2% limited partnership interest in FFHL.</footnote><footnote id="F16">The Reporting Person's indirect interest in these shares includes an 86.5% limited partnership interest in FFHL, a .5% general partner interest in FFHL, and an interest (through the 1990 Trust) in FFC Holdings, Inc., the other .5% general partner of FFHL.</footnote></footnotes><remarks/><ownerSignature><signatureName>David W. Mann</signatureName><signatureDate>2003-08-19</signatureDate></ownerSignature></ownershipDocument>

