Exhibit 5.1

		140 Scott Drive
		Menlo Park, California 94025
		Tel: +1.650.328.4600 Fax: +1.650.463.2600
		www.lw.com
		FIRM / AFFILIATE OFFICES
		Beijing		Moscow
		Boston		Munich
		Brussels		New York
		Century City		Orange County
		Chicago		Paris
		Dubai		Riyadh
February 13, 2020		Düsseldorf		San Diego
		Frankfurt		San Francisco
		Hamburg		Seoul
		Hong Kong		Shanghai
		Houston		Silicon Valley
Zosano Pharma Corporation 34790 Ardentech Court Fremont, CA 94555		London		Singapore
		Los Angeles		Tokyo
		Madrid		Washington, D.C.
		Milan

Ladies and Gentlemen:

We have acted as special counsel to Zosano Pharma Corporation, a Delaware corporation (the “Company”), in connection with the proposed issuance of (A) up to 11,992,307 shares (the “Shares”) of common stock, par value $0.0001 per share (the “Common Stock”), of the Company, (B) Series C Common Stock Purchase Warrants (the “Series C Warrants”) exercisable for up to 14,153,846 shares of Common Stock (the “Series C Warrant Shares”) and (C) Series D Pre-Funded Common Stock Purchase Warrants (the “Pre-Funded Warrants,” and together with the Series C Warrants, the “Warrants”) exercisable for up to 2,161,539 shares of Common Stock (the “Pre-Funded Warrant Shares,” and together with the Series C Warrant Shares, the “Warrant Shares”). The Shares, the Warrants and the Warrant Shares are included in a registration statement on Form S-3 under the Securities Act of 1933, as amended (the “Act”), initially filed with the Securities and Exchange Commission (the “Commission”) on February 14, 2019 (Registration No. 333-229686) (as amended, the “Registration Statement”), and are being offered pursuant to a base prospectus dated March 27, 2019 (the “Base Prospectus”), a preliminary prospectus supplement dated February 11, 2020 filed with the Commission pursuant to Rule 424(b) under the Act and a prospectus supplement filed with the Commission on February 13, 2020 pursuant to Rule 424(b) under the Act (the “Prospectus Supplement,” and together with the Base Prospectus, the “Prospectus”). The Shares and the Warrants are being sold pursuant to an underwriting agreement dated February 12, 2020 between H.C. Wainwright & Co., LLC and the Company (the “Underwriting Agreement”).

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 and the Warrants.

February 13, 2020

Page 2

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 (the “DGCL”), 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:

In rendering the opinions set forth in numbered paragraphs 1, 3 and 4, we have assumed that the Company will comply with all applicable notice requirements regarding uncertificated shares provided in the DGCL.

February 13, 2020

Page 3

Our opinions set forth in numbered paragraph 2 are subject to: (i) the effect of bankruptcy, insolvency, reorganization, fraudulent transfer, moratorium or other similar laws relating to or affecting the rights and remedies of creditors; (ii) the effect of general principles of equity, whether considered in a proceeding in equity or at law (including the possible unavailability of specific performance or injunctive relief), concepts of materiality, reasonableness, good faith and fair dealing, and the discretion of the court before which a proceeding is brought; and (iii) we express no opinion as to (a) any provision for liquidated damages, monetary penalties or other economic remedies to the extent such provisions are deemed to constitute a penalty, (b) consents to, or restrictions upon, governing law, jurisdiction, venue, arbitration, remedies, or judicial relief, (c) waivers of rights or defenses, (d) any provision requiring the payment of attorneys’ fees, where such payment is contrary to law or public policy, (e) advance waivers of claims, defenses, rights granted by law, or notice, opportunity for hearing, evidentiary requirements, statutes of limitation, trial by jury or at law, or other procedural rights, (f) waivers of broadly or vaguely stated rights, (g) provisions for exclusivity, election or cumulation of rights or remedies, (h) provisions authorizing or validating conclusive or discretionary determinations, (i) proxies, powers and trusts, (j) provisions prohibiting, restricting, or requiring consent to assignment or transfer of any right or property, and (k) the severability, if invalid, of provisions to the foregoing effect.

With your consent, we have assumed (a) that the Warrants constitute or will constitute legally valid and binding obligations of the parties thereto other than the Company, enforceable against each of them in accordance with their respective terms and (b) that the status of the Warrants as legally valid and binding obligations of the parties will not be affected by any (i) breaches of, or defaults under, agreements or instruments, (ii) violations of statutes, rules, regulations or court or governmental orders, or (iii) failures to obtain required consents, approvals or authorizations from, or to make required registrations, declarations or filings with, governmental authorities.

This opinion is for your benefit in connection with the Registration Statement and may be relied upon by you and by persons entitled to rely upon it pursuant to the applicable provisions of the Act. We consent to your filing this opinion as an exhibit to the Company’s Current Report on Form 8-K dated February 13, 2020 and to the reference to our firm in the Prospectus under the heading “Legal Matters.” In giving such consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Commission thereunder.