-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 VbMmptCCRKgVIwvWCDOg1Q2EgrSPkAIovsu54U5lvR8XqyLOT96QkR2/chbWcpQ7
 cj7srU+rTMyMjiMcD8nf8g==

<SEC-DOCUMENT>0001252913-10-000002.txt : 20100521
<SEC-HEADER>0001252913-10-000002.hdr.sgml : 20100521
<ACCEPTANCE-DATETIME>20100521100559
ACCESSION NUMBER:		0001252913-10-000002
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		2
CONFORMED PERIOD OF REPORT:	20100414
FILED AS OF DATE:		20100521
DATE AS OF CHANGE:		20100521

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Flaherty & Crumrine PREFERRED INCOME OPPORTUNITY FUND INC
		CENTRAL INDEX KEY:			0000882071
		IRS NUMBER:				954355600
		STATE OF INCORPORATION:			MD
		FISCAL YEAR END:			1130

	BUSINESS ADDRESS:	
		STREET 1:		301 E COLORADO BLVD STE 720
		STREET 2:		C/O FLAHERTY & CRUMRINE INC
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91101
		BUSINESS PHONE:		(626) 795-7300

	MAIL ADDRESS:	
		STREET 1:		301 COLORADO BLVD STE 720
		STREET 2:		C/O FLAHERTY & CRUMRINE INC
		CITY:			PASADENA
		STATE:			CA
		ZIP:			91101

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	PREFERRED INCOME OPPORTUNITY FUND INC
		DATE OF NAME CHANGE:	19920929

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			WULF ROBERT F
		CENTRAL INDEX KEY:			0001252913

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	811-06495
		FILM NUMBER:		10849710

	MAIL ADDRESS:	
		STREET 1:		P.O. BOX 753
		CITY:			NESKOWIN
		STATE:			OR
		ZIP:			97149
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-04-14</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000882071</issuerCik>
        <issuerName>Flaherty &amp; Crumrine PREFERRED INCOME OPPORTUNITY FUND INC</issuerName>
        <issuerTradingSymbol>PFO</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001252913</rptOwnerCik>
            <rptOwnerName>WULF ROBERT F</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>P.O. BOX 753</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NESKOWIN</rptOwnerCity>
            <rptOwnerState>OR</rptOwnerState>
            <rptOwnerZipCode>97149</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>2010-04-14</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>0.6383</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>9.9</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1024</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <ownerSignature>
        <signatureName>Chad Conwell</signatureName>
        <signatureDate>2010-05-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
<DOCUMENT>
<TYPE>EX-24
<SEQUENCE>2
<FILENAME>poarobertwulf.txt
<DESCRIPTION>POWER OF ATTORNEY
<TEXT>


POWER OF ATTORNEY


	KNOW ALL MEN BY THESE PRESENTS, that the
person whose name appears below nominates, constitutes and
appoints Chad C. Conwell, Donald F. Crumrine and Robert M. Ettinger
(with full power to act alone) his true and lawful attorney-
in-fact and agent, for him and on his behalf and in his place and
stead in any and all capacities, to execute any and all filings on
Form 4 (Statement of Changes of Beneficial Ownership of
Securities) pursuant to Section 16(a) of the Securities Exchange
Act of 1934 and Section 30(h) of the Investment Company Act
of 1940, as amended ("Form 4 Filings") with respect to changes
of beneficial ownership of securities of FLAHERTY &
CRUMRINE PREFERRED INCOME FUND INCORPORATED
(the "Fund"), and to file with the Securities and Exchange
Commission, The New York Stock Exchange and the Fund such
Form 4 Filings, granting unto said attorney, full power and
authority to do and perform certain acts and things requisite and
necessary to be done in and about the premises as fully to all
intents and purposes as the undersigned himself might or could do.

	IN WITNESS WHEREOF, the undersigned has hereunto
set his hand this 31st day of December, 2009.



/s/ Robert F. Wulf
Name: Robert F. Wulf
Title:   Director, Flaherty & Crumrine Preferred Income Fund
Incorporated


EXPIRES:  January 1, 2011

</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----
