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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2009-03-31</periodOfReport>

    <issuer>
        <issuerCik>0001401521</issuerCik>
        <issuerName>UNITED INSURANCE HOLDINGS CORP.</issuerName>
        <issuerTradingSymbol>UIHC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001319244</rptOwnerCik>
            <rptOwnerName>INTEGRATED CORE STRATEGIES (US) LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MILLENNIUM MANAGEMENT LLC</rptOwnerStreet1>
            <rptOwnerStreet2>666 FIFTH AVENUE, 8TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10103-0899</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>May be deemed a group member.</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001132413</rptOwnerCik>
            <rptOwnerName>MILLENCO LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MILLENNIUM MANAGEMENT LLC</rptOwnerStreet1>
            <rptOwnerStreet2>666 FIFTH AVENUE, 8TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10103-0899</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>May be deemed a group member.</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001273087</rptOwnerCik>
            <rptOwnerName>MILLENNIUM MANAGEMENT LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>666 FIFTH AVENUE, 8TH FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10103-0899</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>May be deemed a group member.</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001017456</rptOwnerCik>
            <rptOwnerName>ENGLANDER ISRAEL A</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MILLENNIUM MANAGEMENT LLC</rptOwnerStreet1>
            <rptOwnerStreet2>666 FIFTH AVENUE, 8TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10103-0899</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>May be deemed a group member.</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>542400</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrant</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>6.00</value>
                <footnoteId id="F3"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2009-03-31</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>50000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>.7045</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2009-01-02</value>
                <footnoteId id="F3"/>
            </exerciseDate>
            <expirationDate>
                <value>2011-10-04</value>
                <footnoteId id="F3"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>50000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>925575</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">As of the date of this filing, Millenco LLC, a Delaware limited liability company (&quot;Millenco&quot;), is the beneficial owner of 542,400 shares of the common stock, par value $0.0001 per share (&quot;Common Stock&quot;), of United Insurance Holdings Corp., a Delaware corporation (the &quot;Issuer&quot;).</footnote>
        <footnote id="F2">As of the date of this filing, Integrated Core Strategies (US) LLC, a Delaware limited liability company (&quot;Integrated Core Strategies&quot;), holds warrants (&quot;Warrants&quot;) to purchase 925,575 shares of the Issuer's Common Stock, and is therefore the beneficial owner of 925,575 shares of the Issuer's Common Stock.</footnote>
        <footnote id="F3">Each Warrant entitles the holder to purchase one share of the Issuer's Common Stock at a price of $6.00 per share. The Warrants will expire on October 4, 2011, unless redeemed earlier.</footnote>
        <footnote id="F4">Millennium Management LLC, a Delaware limited liability company (&quot;Millennium Management&quot;), is the general partner of the managing member of Integrated Core Strategies, and may be deemed to have shared voting control and investment discretion over securities owned by Integrated Core Strategies. Millennium Management is also the manager of Millenco, and may also be deemed to have shared voting control and investment discretion over securities owned by Millenco.</footnote>
        <footnote id="F5">Israel A. Englander (&quot;Mr. Englander&quot;) is the managing member of Millennium Management. Consequently, Mr. Englander may be deemed to have shared voting control and investment discretion over securities beneficially owned by Integrated Core Strategies and/or Millenco.</footnote>
        <footnote id="F6">The foregoing should not be construed in and of itself as an admission by Millennium Management or Mr. Englander as to beneficial ownership of the securities owned by Integrated Core Strategies and/or Millenco.</footnote>
    </footnotes>

    <remarks>*Integrated Core Strategies (US) LLC, By: Integrated Holding Group LP, its managing member, By: Millennium Management LLC, its general partner, By: David Nolan, Co-President</remarks>

    <ownerSignature>
        <signatureName>*David Nolan, Co-President</signatureName>
        <signatureDate>2009-04-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
