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Prospectus Supplement No. 3 (to Prospectus dated October 16, 2009)		Filed Pursuant to Rule 424(b)(3) Registration No. 333-161804

15,000,000 Shares

Alexza Pharmaceuticals, Inc.

Common Stock

This prospectus supplement supplements the prospectus dated October 16, 2009 (the “Prospectus”), as supplemented by that certain Prospectus Supplement No. 1 dated November 9, 2009 (“Supplement No. 1”) and by that certain Prospectus Supplement No. 2 dated December 16, 2009 (“Supplement No. 2”), which forms a part of our Registration Statement on Form S-1 (Registration No. 333-161804). This prospectus supplement is being filed to update and supplement the information in the Prospectus, Supplement No. 1 and Supplement No. 2 with the information contained in our current report on Form 8-K, filed with the Securities and Exchange Commission (the “Commission”) on December 30, 2009 (the “Current Report”). Accordingly, we have attached the Current Report to this prospectus supplement.

The Prospectus, Supplement No. 1, Supplement No. 2 and this prospectus supplement relate to the offer and sale of up to 15,000,000 shares of our common stock, which includes up to 5,000,000 shares of our common stock issuable upon the exercise of warrants, by the selling stockholders listed on page 29 of the Prospectus, including their transferees, pledgees or donees or their respective successors. We will not receive any proceeds from any resale of the shares of common stock being offered by the Prospectus, Supplement No. 1, Supplement No. 2 and this prospectus supplement.

This prospectus supplement should be read in conjunction with the Prospectus, Supplement No. 1 and Supplement No. 2. This prospectus supplement updates and supplements the information in the Prospectus, Supplement No. 1 and Supplement No. 2. If there is any inconsistency between the information in the Prospectus, Supplement No. 1, Supplement No. 2 and this prospectus supplement, you should rely on the information in this prospectus supplement.

Our common stock is traded on the Nasdaq Global Market under the trading symbol “ALXA.” On December 30, 2009, the last reported sale price of our common stock was $2.28 per share.

Investing in our securities involves a high degree of risk. You should review carefully the risks and uncertainties described under the heading “Risk Factors” beginning on page 3 of the Prospectus and beginning on page 34 of our quarterly report on Form 10-Q for the quarterly period ended September 30, 2009 before you decide whether to invest in shares of our common stock.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if the Prospectus, Supplement No. 1, Supplement No. 2 or this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus supplement is December 31, 2009

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT
Pursuant to Section 13 OR 15(d) of
The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): December 28, 2009

ALEXZA PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)


Delaware	000-51820	77-0567768
(State or other jurisdiction of incorporation)	(Commission File Number)	(IRS Employer Identification No.)


Alexza Pharmaceuticals, Inc. 2091 Stierlin Court Mountain View, California		94043

(Address of principal executive offices)		(Zip Code)

Registrant’s telephone number, including area code: (650) 944-7000

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):


o		Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)


o		Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)


o		Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))


o		Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Section 5 — Corporate Governance and Management

Item 5.02. Departure of Directors or Certain Officers; Election of Directors; Appointment of Certain Officers; Compensatory Arrangements of Certain Officers.

(e) On December 28, 2009, the Board of Directors (the “Board”) of Alexza Pharmaceuticals, Inc. (the “Company”) granted stock option awards to its officers pursuant to the Company’s 2009-2010 Performance Based Incentive Program (the “Performance Program”), the terms of which were described in the Form 8-K filed by the Company on February 24, 2009. The following chart sets forth the stock option award issuances made to the Company’s executive officers related to the Second Milestone under the Performance Program:


Executive Officer	Stock Option Awards
Thomas B. King President and Chief Executive Officer		99,219

James V. Cassella, Ph.D. Senior Vice President, Research and Development		49,626

August J. Moretti Senior Vice President, Chief Financial Officer and Secretary		49,626

Michael J. Simms Senior Vice President, Operations and Quality		49,626

Under the terms of the Performance Program, the stock option awards will vest 50% upon the achievement of the approval of the New Drug Application (“NDA”) for the Company’s AZ-004 (Staccato loxapine) product candidate (the “Second Milestone”), and 50% on the first annual anniversary of the achievement of the Second Milestone. Alexza’s NDA for AZ-004 was submitted on December 11, 2009.

The stock option awards were granted under and in accordance with the terms and conditions of the Company’s 2005 Equity Incentive Plan (which was filed as Exhibit 10.4 to the Company’s Registration Statement on Form S-1 (No. 333-130644), the “2005 Equity Incentive Plan”). All of the stock option awards are ten (10) year options to purchase shares of the Company’s Common Stock, have an exercise price of $2.37 per share and are intended to be incentive stock options for tax purposes. With the exception of the vesting terms, which are set forth above, the form option grant notice relating to the stock option awards conforms to the standard form of option grant notice filed as Exhibit 10.5 to the Company’s Registration Statement on Form S-1 (No. 333-130644).

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.


	Alexza Pharmaceuticals, Inc.
Date: December 30, 2009	By:	/s/ Thomas B. King
		Thomas B. King,
		President and Chief Executive Officer