Exhibit 5.1

June 20, 2013

Midstates Petroleum Company, Inc.

4400 Post Oak Parkway, Suite 1900

Houston, Texas 77027

Ladies and Gentlemen:

We have acted as counsel for Midstates Petroleum Company, Inc., a Delaware corporation (the “Company”), and Midstates Petroleum Company LLC, a Delaware limited liability company (“Midstates Sub”), with respect to certain legal matters in connection with the preparation of the Registration Statement on Form S-3 (the “Registration Statement”), filed on or about the date hereof with the Securities and Exchange Commission (the “Commission”), in connection with the registration by the Company under the Securities Act of 1933 (the “Securities Act”) of the offer and sale by the Company from time to time, pursuant to Rule 415 under the Securities Act, of (i) debt securities, which may be either senior or subordinated and may be issued in one or more series, consisting of notes, debentures or other evidences of indebtedness (the “Debt Securities”) and which may be co-issued by Midstates Sub or may be fully and unconditionally guaranteed (the “Guarantee”) by Midstates Sub; (ii) shares of preferred stock, par value $0.01 per share, of the Company, in one or more series (the “Preferred Stock”), which may be issued in the form of depositary shares evidenced by depositary receipts (the “Depositary Shares”); (iii) shares of common stock, par value $0.01 per share, of the Company (the “Common Stock”); and (iv) warrants for the purchase of Common Stock (the “Warrants” and, together with the Debt Securities, the Guarantee, the Preferred Stock, the Depositary Shares and the Common Stock, the “Securities”).

We have also participated in the preparation of the Prospectus (the “Prospectus”) contained in the Registration Statement to which this opinion is an exhibit. The Securities will be offered in amounts, at prices and on terms to be determined in light of market conditions at the time of sale and to be set forth in supplements (each a “Prospectus Supplement”) to the Prospectus. The aggregate initial offering prices of the Securities to be offered and sold by the Company pursuant to the Registration Statement will not exceed $500,000,000.

In connection with the opinions expressed herein, we have examined, among other things, the (i) the Amended and Restated Certificate of Incorporation and the Amended and Restated Bylaws of the Company, (ii) the Certificate of Formation and the Third Amended and Restated Limited Liability Company Agreement of Midstates Sub, (iii) the Registration Statement, (iv) the Prospectus, (v) the form of Senior Indenture (the “Senior Indenture”) filed as an exhibit to the Registration Statement, (vi) the form of Subordinated Indenture (the “Subordinated Indenture,” and together with the Senior Indenture, the “Indentures”) filed as an exhibit to the Registration Statement and (vii) the records of corporate proceedings that have occurred prior to the date hereof with respect to the Registration Statement. We have also reviewed such questions of law as we have deemed necessary or appropriate. As to matters of fact relevant to the opinions expressed herein, and as to factual matters arising in connection with our examination of corporate documents, records and other documents and writings, we relied upon certificates and other communications of corporate officers of the Company, without further investigation as to the facts set forth therein.

In connection with rendering the opinions set forth below, we have assumed that (i) all information contained in all documents reviewed by us is true and correct; (ii) all signatures on all documents examined by us are genuine; (iii) all documents submitted to us as originals are authentic and all documents submitted to us as copies conform to the originals of those documents; (iv) the Registration Statement and any subsequent amendments (including additional post-effective amendments), will have become effective and comply with all applicable laws; (v) all Securities will be issued and sold in compliance with applicable federal and state securities laws and in the manner specified in the Registration Statement and the applicable Prospectus Supplement; (vi) one or more Prospectus Supplements to the Prospectus will have been prepared and filed with the Commission describing the Securities offered thereby; (vii) the Indentures, and any supplemental indenture relating to a particular series of Debt Securities, will be duly authorized, executed and delivered by the parties thereto in substantially the form reviewed

by us; (viii) a definitive purchase, underwriting or similar agreement with respect to any Securities offered will have been duly authorized and validly executed and delivered by the Company and the other parties thereto; (ix) any securities issuable upon conversion, exchange or exercise of any Debt Securities, Preferred Stock, Depositary Shares or Warrants being offered will have been duly authorized, created and, if appropriate, reserved for issuance upon such conversion, exchange or exercise; (x) Midstates Sub is duly incorporated or organized and is validly existing and in good standing under the laws of its jurisdiction of organization; (xi) each person signing the Indentures and the agreements relating to the Warrants will have the legal capacity and authority to do so; and (xii) at the time of any offering or sale of any shares of Common Stock or Preferred Stock, the Company shall have such number of shares of Common Stock or Preferred Stock, as set forth in such offering or sale, authorized or created and available for issuance.

Based on the foregoing, and subject to the assumptions, qualifications, limitations, and exceptions set forth herein, we are of the opinion that:

1.             With respect to the Debt Securities (including, if Debt Securities are guaranteed by Midstates Sub, such Debt Securities and such Guarantee), when (i) the applicable Indenture relating either to senior Debt Securities or subordinated Debt Securities and, if applicable, the related Guarantee have been duly qualified under the Trust Indenture Act of 1939, as amended, (ii) the board of directors (the “Board”) of the Company (or a committee thereof) and the sole member of Midstates Sub has taken all necessary action to approve the issuance and terms of any such Debt Securities and, if applicable, Guarantee, (iii) the terms of such Debt Securities and, if applicable, the related Guarantee, and of their issuance and sale have been duly established in conformity with the applicable Indenture so as not to violate any applicable law or result in a default under or breach of any agreement or instrument binding upon the Company or Midstates Sub and so as to comply with any requirements or restrictions imposed by any court or governmental body having jurisdiction over the Company or Midstates Sub, (iv) any shares of Common Stock issuable upon the conversion of such Debt Securities, if applicable, have been duly and validly authorized for issuance and (v) such Debt Securities (which may include the related Guarantee) have been duly executed and authenticated in accordance with the applicable Indenture and issued and sold as contemplated in the Registration Statement and upon payment of the consideration for such Debt Securities as provided for in the applicable definitive purchase, underwriting or similar agreement, such Debt Securities and, if applicable, the related Guarantee will be legally issued and such Debt Securities and, if applicable, the related Guarantee will constitute valid and legally binding obligations of the Company and Midstates Sub, respectively, enforceable against the Company and Midstates Sub in accordance with their terms, except as such enforcement is subject to any applicable bankruptcy, insolvency (including, without limitation, all laws relating to fraudulent transfers), reorganization, moratorium and similar laws relating to or affecting creditors’ rights generally and to general equitable principles (regardless of whether enforcement is sought in a proceeding in equity or at law);

2.             With respect to shares of Common Stock, when both the Board has taken all necessary corporate action to approve the issuance of and the terms of the offering of the shares of Common Stock and related matters and certificates representing the shares of Common Stock have been duly executed, countersigned, registered, and delivered either (i) in accordance with the applicable definitive purchase, underwriting, or similar agreement approved by the Board or such officers upon payment of the consideration therefor (not less than the par value of the Common Stock) provided for therein or (ii) upon conversion or exercise of any other Security, in accordance with the terms of such Security or the instrument governing such Security providing for such conversion or exercise as approved by the Board, for the consideration approved by the Board (not less than the par value of the Common Stock), then the shares of Common Stock will be legally issued, fully paid, and nonassessable;

3.             With respect to shares of any series of Preferred Stock, when the Board has taken all necessary corporate action to approve the issuance and terms of the shares of the series, the terms of the offering thereof and related matters, including the adoption of a resolution establishing and designating the series and fixing and determining the preferences, limitations and relative rights thereof and the filing of a statement with respect to the series with the Secretary of State of the State of Delaware (the “Certificate of Designation”) and certificates representing the shares of the series of Preferred Stock have been duly executed, countersigned, registered and delivered either (i) in accordance with the applicable definitive purchase, underwriting or similar agreement approved by the Board, then upon payment of the consideration therefor (not less than the par value of the Preferred Stock) provided for therein; or (ii) upon conversion, exchange or exercise of any other Security in accordance with the terms of the Security or the instrument governing the Security providing for the conversion, exchange or exercise as approved by the Board,

for the consideration approved by the Board (not less than the par value of the Preferred Stock), the shares of the series of Preferred Stock will be validly issued, fully paid and non-assessable;

4.             With respect to the Depositary Shares, when (i) the Company has taken all necessary corporate action to approve the issuance and terms of the Depositary Shares, the terms of the offering thereof and related matters, including the adoption of a Certificate of Designation relating to the Preferred Stock underlying the Depositary Shares and the filing of the Certificate of Designation with the Secretary of State of the State of Delaware; (ii) the depositary agreement or agreements relating to the Depositary Shares and the related depositary receipts have been duly authorized and validly executed and delivered by the Company and the depositary appointed by the Company; (iii) the shares of Preferred Stock underlying the Depositary Shares have been deposited with the depositary under the applicable depositary agreement; and (iv) the depositary receipts representing the Depositary Shares have been duly executed, countersigned, registered and delivered in accordance with the appropriate depositary agreement approved by the Company, upon payment of the consideration therefor provided for in the applicable definitive purchase, underwriting or similar agreement, the Depositary Shares will be legally issued; and

5.             With respect to the Warrants, when (i) the Board has taken all necessary corporate action to approve the creation of and the issuance and terms of the Warrants, the terms of the offering thereof, and related matters, (ii) the agreements relating to the Warrants have been duly authorized and validly executed and delivered by the Company and the Warrant Agent appointed by the Company, and (iii) the Warrants or certificates representing the Warrants have been duly executed, countersigned, registered, and delivered in accordance with the appropriate agreements relating to the Warrants and the applicable definitive purchase, underwriting, or similar agreement approved by the Board or such officers upon payment of the consideration therefor provided for therein, the Warrants will be legally issued and such Warrants will constitute valid and legally binding obligations of the Company, enforceable against the Company in accordance with their terms, except as such enforcement is subject to any applicable bankruptcy, insolvency (including, without limitation, all laws relating to fraudulent transfers), reorganization, moratorium and similar laws relating to or affecting creditors’ rights generally and to general equitable principles (regardless of whether enforcement is sought in a proceeding in equity or at law).

With respect to our opinions expressed above, as they relate to Debt Securities denominated in a currency other than U.S. dollars, we note that effective enforcement of a foreign currency claim in the New York State courts or the federal courts sitting in the State of New York may be limited by requirements that the claim (or a foreign currency judgment in respect of such claim) be converted to U.S. dollars at the rate of exchange prevailing on a specified date. We express no opinion as to whether a federal court sitting in the State of New York would award a judgment in a currency other than U.S. dollars.

We express no opinions concerning (i) the validity or enforceability of any provisions contained in the Indentures that purport to waive or not give effect to rights to notices, defenses, subrogation or other rights or benefits that cannot be effectively waived under applicable law or (ii) the enforceability of indemnification provisions to the extent they purport to relate to liabilities resulting from or based upon negligence or any violation of federal or state securities or blue sky laws.

The foregoing opinions are limited to the laws of the States of Delaware and New York, the Delaware General Corporation Law (including the applicable provisions of the Delaware Constitution and the reported judicial decisions interpreting these laws) and the federal laws of the United States of America, and we are expressing no opinion as to the effect of the laws of any other jurisdiction, domestic or foreign.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the use of our name in the Prospectus forming a part of the Registration Statement under the caption “Legal Matters.” In giving this consent, we do not admit that we are within the category of persons whose consent is required under Section 7 of the Securities Act and the rules and regulations thereunder.

Very truly yours,

/s/ Vinson & Elkins L.L.P.