EX-5.1

Exhibit 5.1


	12670 High Bluff Drive
	San Diego, California 92130
	Tel: +1.858.523.5400 Fax: +1.858.523.5450
	www.lw.com
	FIRM / AFFILIATE OFFICES
	Austin	Moscow
	Beijing	Munich
	Boston	New York
	Brussels	Orange County
	Century City	Paris
	Chicago	Riyadh
	Dubai	San Diego
	Düsseldorf	San Francisco
	Frankfurt	Seoul
	Hamburg	Shanghai
April 25, 2022	Hong Kong	Silicon Valley
	Houston	Singapore
	London	Tel Aviv
HilleVax, Inc.	Los Angeles	Tokyo
75 State Street, Suite 100 - #9995	Madrid	Washington, D.C.
Boston, Massachusetts 02109	Milan

Re:

Registration Statement No. 333-264159; 11,838,100 shares of Common Stock, par value $0.0001 per share

Ladies and Gentlemen:

We have acted as special counsel to HilleVax, Inc., a Delaware corporation (the “Company”), in connection with the proposed issuance of up to 11,838,100 shares (including up to 1,544,100 shares subject to the underwriters’ option to purchase additional shares) of common stock, $0.0001 par value per share (the “Shares”). The Shares are included in a registration statement on Form S-1 under the Securities Act of 1933, as amended (the “Act”), filed with the Securities and Exchange Commission (the “Commission”) on April 6, 2022 (File No. 333-264159) (as amended, the “Registration Statement”). The term “Shares” shall include any additional shares of common stock registered by the Company pursuant to Rule 462(b) under the Act in connection with the offering contemplated by the Registration Statement. This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or related Prospectus, other than as expressly stated herein with respect to the issue of the Shares.

As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter. With your consent, we have relied upon certificates and other assurances of officers of the Company and others as to factual matters without having independently verified such factual matters.We are opining herein as to the General Corporation Law of the State of Delaware and we express no opinion with respect to any other laws.

Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, when the Shares shall have been duly registered on the books of the transfer agent and registrar therefor in the name or on behalf of the purchasers, and have been issued by the Company against payment therefor in the circumstances contemplated by the form of underwriting agreement most recently filed as an exhibit to the Registration Statement, the issue and sale of the Shares will have been duly authorized by all necessary corporate action of the Company, and the Shares will be validly issued, fully paid and nonassessable. In rendering the foregoing opinion, we have assumed that the Company will comply with all applicable notice requirements regarding uncertificated shares provided in the General Corporation Law of the State of Delaware.