<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-03-15</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0000726990</issuerCik>
        <issuerName>AMERICANWEST BANCORPORATION</issuerName>
        <issuerTradingSymbol>AWBC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001225423</rptOwnerCik>
            <rptOwnerName>KETELSEN ALLEN FRED</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O AMERICANWEST BANCORPORATION</rptOwnerStreet1>
            <rptOwnerStreet2>41 W. RIVERSIDE AVE. SUITE 400</rptOwnerStreet2>
            <rptOwnerCity>SPOKANE</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>99201</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>2006-03-15</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>721</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14541</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Received in exchange for 400 shares of Columbia Trust Bancorp common stock in connection with merger of Columbia Trust Bancorp into AmericanWest Bancorporation (the&quot;Merger&quot;). The shares were exchanged at an exchange rate of 1 : 1.8035 per share. The shares of AmericanWest Bancorp were valued at $25.34, based on a 20-day average, pursuant to the terms of the agreement. The shares of Columbia Trust Bancorp were valued at $45.70 prior to the effective date of the merger.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ R. Blair Reynolds, Pursuant to Power of Attorney on File</signatureName>
        <signatureDate>2006-04-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0202
4
2006-03-15
1
0000726990
AMERICANWEST BANCORPORATION
AWBC
0001225423
KETELSEN ALLEN FRED
C/O AMERICANWEST BANCORPORATION
41 W. RIVERSIDE AVE. SUITE 400
SPOKANE
WA
99201
1
0
0
0
Common Stock
2006-03-15
4
A
0
721
A
14541
D
Received in exchange for 400 shares of Columbia Trust Bancorp common stock in connection with merger of Columbia Trust Bancorp into AmericanWest Bancorporation (the"Merger"). The shares were exchanged at an exchange rate of 1 : 1.8035 per share. The shares of AmericanWest Bancorp were valued at $25.34, based on a 20-day average, pursuant to the terms of the agreement. The shares of Columbia Trust Bancorp were valued at $45.70 prior to the effective date of the merger.
/s/ R. Blair Reynolds, Pursuant to Power of Attorney on File
2006-04-04