<SUBMISSION>
<ACCESSION-NUMBER>0001309097-07-000003
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20071121
<FILING-DATE>20071210
<DATE-OF-FILING-DATE-CHANGE>20071210
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>Brown Norman H Jr
<CIK>0001309097
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>001-32385
<FILM-NUMBER>071295340
</FILING-VALUES>
<BUSINESS-ADDRESS>
<PHONE>212-548-6538
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>C/O MACQUARIE INFRASTRUCTURE COMPANY LLC
<STREET2>600 FIFTH AVENUE, 21ST FLOOR
<CITY>NEW YORK
<STATE>NY
<ZIP>10020
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>Macquarie Infrastructure CO Trust
<CIK>0001289788
<ASSIGNED-SIC>5172
<IRS-NUMBER>206196808
<STATE-OF-INCORPORATION>DE
<FISCAL-YEAR-END>1231
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>125 WEST 55TH STREET, 22ND FLOOR
<CITY>NEW YORK
<STATE>NY
<ZIP>10019
<PHONE>212-231-1000
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>125 WEST 55TH STREET, 22ND FLOOR
<CITY>NEW YORK
<STATE>NY
<ZIP>10019
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>Macquarie Infrastructure Assets Trust
<DATE-CHANGED>20040510
</FORMER-COMPANY>
</ISSUER>
<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>2007-11-21</periodOfReport>

    <issuer>
        <issuerCik>0001289788</issuerCik>
        <issuerName>Macquarie Infrastructure CO Trust</issuerName>
        <issuerTradingSymbol>MIC</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001309097</rptOwnerCik>
            <rptOwnerName>Brown Norman H Jr</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>125 W 55TH STREET</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>LLC Interest</value>
            </securityTitle>
            <transactionDate>
                <value>2007-11-21</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>625</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15001</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>LLC Interests</value>
            </securityTitle>
            <transactionDate>
                <value>2007-11-29</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>G</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>100</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14901</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes></footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Heidi Mortensen, Attorney-in-Fact</signatureName>
        <signatureDate>2007-12-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
