Exhibit 5.1

Nicole C. Brookshire

+1 617 937 2357

nbrookshire@cooley.com

December 5, 2019

Millendo Therapeutics, Inc.

301 North Main Street, Suite 100

Ann Arbor, Michigan 48104

Ladies and Gentlemen:

We have acted as counsel to Millendo Therapeutics, Inc., a Delaware corporation (the “Company”), with respect to certain matters in connection with the offering by the Company of up to 4,791,667 shares of the Company’s common stock, par value $0.001 per share (the “Shares”), including up to 625,000 Shares that may be sold upon exercise of an option to purchase additional Shares, pursuant to that certain Underwriting Agreement (the “Agreement”), dated December 4, 2019, by and among the Company and the underwriters named therein, and pursuant to a Registration Statement on Form S-3 (File No. 333-230749) (the “Registration Statement”), filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Act”), the related prospectus dated April 5, 2019 (the “Base Prospectus”) and the prospectus supplement, dated December 4, 2019, related to the Shares, as filed with the Commission pursuant to Rule 424(b) under the Act (together with the Base Prospectus, the “Prospectus”).

In connection with this opinion, we have examined and relied upon (a) the Registration Statement and the Prospectus, (b) the Company’s certificate of incorporation and bylaws, each as currently in effect, and (c) originals or copies certified to our satisfaction of such records, documents, certificates, opinions, memoranda and other instruments as in our judgment are necessary or appropriate to enable us to render the opinion expressed below. We have assumed the genuineness and authenticity of all documents submitted to us as originals, the conformity to originals of all documents submitted to us as copies thereof, the accuracy, completeness and authenticity of certificates of public officials and the due authorization, execution and delivery of all documents by persons other than the Company where authorization, execution and delivery are a prerequisite to the effectiveness thereof. As to certain factual matters, we have relied upon a certificate of an officer of the Company and have not sought independently to verify such matters.

Our opinion is expressed only with respect to the General Corporation Law of the State of Delaware. We express no opinion to the extent that any other laws are applicable to the subject matter hereof and express no opinion and provide no assurance as to compliance with any federal or state securities law, rule or regulation.

On the basis of the foregoing, and in reliance thereon, we are of the opinion that the Shares, when sold in accordance with the Agreement, the Registration Statement and the Prospectus, will be validly issued, fully paid and non-assessable.

We consent to the reference to our firm under the caption “Legal Matters” in the Prospectus and to the filing of this opinion as an exhibit to a Current Report on Form 8-K to be filed with the Commission for incorporation by reference into the Registration Statement.

Cooley LLP 500 Boylston Street Boston, MA 02116-3736
t: (617) 937-2300 f: (617) 937-2400 cooley.com

December 5, 2019

Page Two

Sincerely,

Cooley LLP

By:	/s/ Nicole C. Brookshire
	Nicole C. Brookshire

Cooley LLP 500 Boylston Street Boston, MA 02116-3736
t: (617) 937-2300 f: (617) 937-2400 cooley.com