Exhibit 5.1

May 28, 2024

Reviva Pharmaceuticals Holdings, Inc.

19925 Stevens Creek Blvd., Suite 100

Cupertino, California 95014

Ladies and Gentlemen:

We have acted as counsel to Reviva Pharmaceuticals Holdings, Inc., a Delaware corporation (the “Company”), in connection with (i) the preparation and filing of the Registration Statement on Form S-3 (Registration No. 333-262348) filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Securities Act”), (as so filed, the “Registration Statement”) and the related prospectus contained in the Registration Statement and (ii) the preparation and filing of the prospectus supplement, dated May 28, 2024 (the “Prospectus Supplement”) relating to the issuance and sale by the Company of (i) 1,898,734 shares (the “Shares”) of common stock of the Company, par value $0.0001 (the “Common Stock”), and (ii) warrants to purchase up to 1,898,734 shares of Common Stock (each a “Warrant,” and each share of Common Stock underlying such Warrant, a “Warrant Share”).

The Shares, Warrants and the Warrant Shares are to be issued and sold by the Company pursuant to the Securities Purchase Agreement, dated as of May 28, 2024 (the “Purchase Agreement”), between the Company and the purchaser signatory thereto, the form of which is being filed with the Commission as Exhibit 10.1 to the Company’s Current Report on Form 8-K, filed on the date hereof.

In connection with this opinion, we have (i) investigated such questions of law, (ii) examined originals or certified, conformed or reproduction copies of such agreements, instruments, documents and records of the Company, such certificates of public officials and such other documents, and (iii) received such information from officers and representatives of the Company as we have deemed necessary or appropriate for the purposes of this opinion.

In all such examinations, we have assumed the legal capacity of all natural persons, the genuineness of all signatures, the authenticity of original and certified documents and the conformity to original or certified documents of all copies submitted to us as conformed or reproduction copies. As to various questions of fact relevant to the opinion expressed herein, we have relied upon, and assume the accuracy of, the representations and warranties set forth in the Purchase Agreement, and certificates and oral or written statements and other information of or from public officials and officers and representatives of the Company.

Based upon the foregoing and subject to the limitations, qualifications and assumptions set forth herein, we are of the opinion that (i) the Shares have been duly authorized and, when issued and paid for in accordance with the terms of the Purchase Agreement, will be validly issued, fully paid and non-assessable, (ii) the Warrants have been duly authorized and, when executed and delivered by the Company will constitute the legal, valid and binding obligation of the Company, enforceable against the Company in accordance with their terms, subject to bankruptcy, insolvency or other similar laws affecting creditors’ rights and to general equitable principles, and (iii) the Warrant Shares have been duly authorized and, when issued and paid for upon the due exercise of the Warrants, as applicable, in accordance with the terms thereof, will be validly issued, fully paid and non-assessable.

The opinion expressed herein is limited to the applicable provisions of the General Corporation Law of the State of Delaware (the “DGCL”), as currently in effect, and reported judicial decisions interpreting such provisions of the DGCL.

The opinion expressed herein is limited to the matters stated herein and no opinion is implied or may be inferred beyond the matters expressly stated herein. We undertake no obligation to supplement this letter if any applicable laws change after the date hereof or if we become aware of any facts that might change the opinion expressed herein after that date or for any other reason.

We hereby consent to the inclusion of this opinion as an exhibit to a Current Report on Form 8-K to be filed by the Company with the Commission, which Current Report on Form 8-K will be incorporated by reference into the Registration Statement, and to the references to our firm under the caption “Legal Matters” in the Prospectus Supplement. In giving our consent, we do not admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations thereunder. 

Very truly yours,

/s/ Lowenstein Sandler LLP

Lowenstein Sandler LLP