Exhibit 5.1

June 30, 2011

United States Securities and Exchange Commission
100 F Street N.E.
Washington, D.C. 20549

Re:                             Kodiak Oil & Gas Corp.

Ladies and Gentlemen:

We have acted as corporate counsel to Kodiak Oil & Gas Corp., a company existing under the laws of the Yukon Territory (the “Company”), in connection with the registration by the Company pursuant to the registration statement (the “Registration Statement”) on Form S-3 (File No. 333-173520) filed with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Securities Act”), the related prospectus, dated June 29, 2011 (the “Prospectus”), and the prospectus supplement thereto, dated June 30, 2011 (the  “Prospectus Supplement”), relating to the resale of 2,500,000 common shares, no par value, of the Company (the “Shares”) for the account of the selling shareholder identified in the Prospectus Supplement.  The Shares are being issued in accordance with the terms of a purchase and sale agreement dated May 20, 2011 among the Company, Kodiak Oil & Gas (USA) Inc. and Ursa Resources Group LLC (the “Agreement”).

We have examined the Registration Statements, the Prospectus and the Prospectus Supplement and, for the purposes of this opinion, we have also examined the originals, or duplicate, certified, conformed, telecopied or photostatic copies, of such corporate records, agreements, documents and other instruments and have made such other investigations as we have considered necessary or relevant for the purposes of this opinion. With respect to the accuracy of factual matters material to this opinion, we have relied upon the financial statements of the Company, certificates or comparable documents and representations of public officials and of officers and representatives of the Company.

In giving this opinion, we have assumed the genuineness of all signatures, the legal capacity of natural persons, the authenticity of all documents submitted to us as originals, the conformity to authentic original documents of all documents submitted to us as duplicates, certified, conformed, telecopied or photostatic copies and the authenticity of the originals of such latter documents.   We have also assumed that the Shares have been issued in accordance with the terms of the Agreement.

We are qualified to express opinions with respect to the laws of the Yukon Territory and the federal laws of Canada applicable therein. We express no opinion on the laws of any jurisdiction other than the Yukon Territory and the federal laws of Canada applicable therein.

Based and relying upon the foregoing, and subject to the qualifications, assumptions and limitations stated herein, we are of the opinion that the Shares have been duly authorized and validly issued as fully paid and non-assessable common shares in the capital of the Company.

Certain partners of Miller Thomson LLP own 15,500 common shares in the capital of the Company.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the Registration Statement and to the use of our name under the caption “Interests of Named Experts and Counsel.”

Yours truly,

/s/  “Miller Thomson LLP”