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

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2006-03-28</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001132645</issuerCik>
        <issuerName>TRANSMERIDIAN EXPLORATION INC</issuerName>
        <issuerTradingSymbol>TMY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001286714</rptOwnerCik>
            <rptOwnerName>OLIVIER LORRIE T</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>397 N. SAM HOUSTON PWKY E</rptOwnerStreet1>
            <rptOwnerStreet2>SUITE 300</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77060</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CHAIRMAN/CEO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Put Option (right to sell)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <footnoteId id="F1"/>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2006-03-28</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>2500000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2006-03-28</value>
            </exerciseDate>
            <expirationDate>
                <value>2008-03-28</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>2500000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2500000</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>The Olivier Family Trust</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On March 28, 2006, The Olivier Family Trust (the &quot;Trust&quot;) borrowed on a non-recourse basis the principal sum of approximately $6.4 million (the &quot;Loan&quot;) from a non-affiliated lender (the &quot;Lender&quot;).  The Loan matures on March 28, 2008.  As collateral for the Loan, the Trust pledged to the Lender 2,500,000 restricted shares of Common Stock (the &quot;Pledged Shares&quot;).  The Loan and pledge provide that if the Trust fails to repay the Loan at maturity, or if an event of default on the Loan occurs at an earlier date, the Lender may sell the Pledged Shares to satisfy the unpaid balance of the amount owed; however, the Trust would not be liable for any deficiency if the Pledged Stock, or proceeds thereof, is not sufficient to satisfy in full all amounts owed.  At all times prior to the occurrence of an event of default, the Trust retains sole voting power over the Pledged Shares and the right to receive any dividends or distributions thereon.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Lorrie T. Olivier</signatureName>
        <signatureDate>2006-03-30</signatureDate>
    </ownerSignature>
</ownershipDocument>
