Exhibit 5.1

MICHAEL E. TENTA

+1 650 843 5636

mtenta@cooley.com

August 2, 2017

Aduro Biotech, Inc.

740 Heinz Avenue

Berkeley, CA 94710

Ladies and Gentlemen:

We have acted as counsel to Aduro Biotech, Inc., a Delaware corporation (the “Company”), in connection with the filing of a Registration Statement on Form S-3 (the “Registration Statement”) by the Company under the Securities Act of 1933, as amended (the “Securities Act”) covering the resale by certain selling stockholders identified in the Registration Statement of up to 25,408,031 shares of the Company’s Common Stock, par value $0.0001 per share (the “Shares”).

In connection with this opinion, we have examined the Registration Statement and the related prospectus included therein (the “Prospectus”), the Company’s Certificate of Incorporation and Bylaws, each as currently in effect, and such other documents, records, certificates, memoranda and other instruments as in our judgement are necessary or appropriate to render the opinion expressed below. In rendering this opinion, we have assumed the genuineness and authenticity of all signatures on original documents; the genuineness and authenticity of all documents submitted to us as originals; the conformity to originals of all documents submitted to us as copies; and the accuracy, completeness and authenticity of certificates of public officials. 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 herein is expressed solely with respect to the General Corporation Law of the State of Delaware. Our opinion is based on these laws as in effect on the date hereof, and we disclaim any obligation to advise you of facts, circumstances, events or developments which hereafter may be brought to our attention and which may alter, affect or modify the opinion expressed herein. We express no opinion as to whether the laws of any particular jurisdiction other than those identified above are applicable to the subject matter hereof. We are not rendering any opinion as to compliance with any federal or state law, rule or regulation relating to securities, or to the sale or issuance thereof.

On the basis of the foregoing and in reliance thereon, and subject to the qualifications herein stated, we are of the opinion that the Shares were validly issued and are fully paid and nonassessable.

COOLEY LLP 3175 HANOVER STREET PALO ALTO, CA 94304-1130

T: (650) 843-5000 F: (650) 849-7400 COOLEY.COM

August 2, 2017

Page Two

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the reference to our firm under the caption “Legal Matters” in the Prospectus.

Sincerely,

Cooley LLP
By:	/s/ Michael E. Tenta
	Michael E. Tenta

COOLEY LLP 3175 HANOVER STREET PALO ALTO, CA 94304-1130

T: (650) 843-5000 F: (650) 849-7400 COOLEY.COM