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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 VIjHY8Qdeq4UYkYkb5qbgEirc5JSKQhuQx9Ju/BlwN0X+Fh7SD4O6uKMGgVARuqh
 lBz2Aj+lyWzxeI34qyYDJg==

<SEC-DOCUMENT>0001209191-08-026844.txt : 20080501
<SEC-HEADER>0001209191-08-026844.hdr.sgml : 20080501
<ACCEPTANCE-DATETIME>20080501161705
ACCESSION NUMBER:		0001209191-08-026844
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20080430
FILED AS OF DATE:		20080501
DATE AS OF CHANGE:		20080501

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			Alexza Pharmaceuticals Inc.
		CENTRAL INDEX KEY:			0001344413
		STANDARD INDUSTRIAL CLASSIFICATION:	PHARMACEUTICAL PREPARATIONS [2834]
		IRS NUMBER:				770567768
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2091 STIERLIN COURT
		CITY:			MOUNTAIN VIEW
		STATE:			CA
		ZIP:			94043
		BUSINESS PHONE:		650.944.7000

	MAIL ADDRESS:	
		STREET 1:		2091 STIERLIN COURT
		CITY:			MOUNTAIN VIEW
		STATE:			CA
		ZIP:			94043

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			KING THOMAS BRAXTON
		CENTRAL INDEX KEY:			0001279309

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	000-51820
		FILM NUMBER:		08794969

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		8015605193

	MAIL ADDRESS:	
		STREET 1:		91 JAMES AVENUE
		CITY:			ATHERTON
		STATE:			CA
		ZIP:			94027
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>bdn55257_bdn3tbk.xml
<DESCRIPTION>MAIN DOCUMENT DESCRIPTION
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0202</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-04-30</periodOfReport>

    <issuer>
        <issuerCik>0001344413</issuerCik>
        <issuerName>Alexza Pharmaceuticals Inc.</issuerName>
        <issuerTradingSymbol>ALXA</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001279309</rptOwnerCik>
            <rptOwnerName>KING THOMAS BRAXTON</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>ALEXZA PHARMACEUTICALS INC.</rptOwnerStreet1>
            <rptOwnerStreet2>2091 STIERLIN COURT</rptOwnerStreet2>
            <rptOwnerCity>MOUNTAIN VIEW</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94043</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Pres &amp; CEO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7368</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>141107</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By The Thomas and Beth King 2000 Family Trust, as co-trustees</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Includes 3,188 shares acquired under the Alexza Pharmaceuticals, Inc. 2005 Employee Stock Purchase Plan on April 30, 2008.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Brent D. Fassett, Attorney-in-Fact</signatureName>
        <signatureDate>2008-05-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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