Exhibit 5.1

[Bryan Cave LLP Letterhead]

May 3, 2017

Centene Corporation

7700 Forsyth Boulevard

St. Louis, Missouri 63105

Re: Registration Statement on Form S-3

Ladies and Gentlemen:

We have acted as counsel to Centene Corporation, a Delaware corporation (the “Company”), in connection with the Company’s filing of a Registration Statement on Form S-3 (the “Registration Statement”) with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Act”), relating to (i) debt securities of the Company (the “Debt Securities”); (ii) shares of common stock of the Company, par value $0.001 per share (the “Common Stock”); (iii) shares of preferred stock of the Company, par value $0.001 per share, (the “Preferred Stock”), which may be represented by depositary shares (the “Depositary Shares”) evidenced by depositary receipts (the “Receipts”); and (iv) warrants or other rights to purchase Debt Securities, Common Stock or Preferred Stock (the “Warrants,” and collectively with the Debt Securities, Common Stock, Preferred Stock and Depositary Shares, the “Securities”). An indeterminate amount of the Securities may be offered at indeterminate prices from time to time by the Company pursuant to Rule 415 under the Act as set forth in the Registration Statement, any amendment thereto, the prospectus contained therein and supplements to the prospectus.

We understand that (i) the Debt Securities will be issued under an Indenture (the “Indenture”) entered or to be entered into between the Company and The Bank of New York Mellon Trust Company, N.A., as trustee (the “Trustee”); (ii) the Depositary Shares will be issued pursuant to a deposit agreement (the “Deposit Agreement”) between the Company and a depositary agent to be specified therein (the “Depositary Agent”) and (iii) the Warrants will be issued under a warrant agreement (the “Warrant Agreement”) between the Company and a bank or trust company, as warrant agent to be specified therein (the “Warrant Agent”).

In connection herewith, we have examined the Registration Statement (including the Indenture or form of Indenture and the other exhibits thereto). We have also examined originals or copies, certified or otherwise identified to our satisfaction, of the Company’s certificate of incorporation and bylaws and such other corporate records, agreements and instruments of the Company, certificates of public officials and officers of the Company, and such other documents, records and instruments, and we have made such legal and factual inquiries, as we have deemed necessary or appropriate as a basis for us to render the opinions hereinafter expressed. In our examination of the foregoing, we have assumed the genuineness of all signatures, the legal competence and capacity of natural persons, the authenticity of documents submitted to us as originals and the conformity with authentic original documents of all documents submitted to us as copies or by facsimile or other means of electronic transmission, or which we obtained from the Commission’s Electronic Data Gathering, Analysis and Retrieval system (“Edgar”) or other sites maintained by a court or governmental authority or regulatory body and the authenticity of the originals of such latter documents. If any document we examined in printed, word processed or similar form has been filed with the Commission on Edgar or such court or governmental authority or regulatory body, we have assumed that the document so filed is identical to the document we examined except for formatting changes. When relevant facts were not independently established, we have relied without independent investigation as to matters of fact upon statements of governmental officials and upon representations made in or pursuant to certificates or statements of appropriate representatives of the Company.

We also have assumed that: (1) at the time of execution, authentication, issuance and delivery of the Debt Securities, the Indenture will have been duly authorized, executed and delivered by the Company and the Trustee, will be in full force and effect, will not have been terminated or rescinded by the Company or the Trustee and will be the valid and legally binding obligation of the Trustee, enforceable against such party in accordance with its terms; (2) at the time of execution, issuance and delivery of any Receipts, the related Deposit Agreement will have been duly authorized, executed and delivered by the Company and the Depositary Agent, will be in full force and effect, will not have been terminated or rescinded by the Company or the Depositary Agent and will be the valid and legally binding obligation of the Depositary Agent, enforceable against such party in accordance with its terms; (3) at the time of execution, countersignature, issuance and delivery of any Warrants, the related Warrant Agreement will have been duly authorized, executed and delivered by the Company and the Warrant Agent, will be in full force and effect, will not have been terminated or rescinded by the Company or the Warrant Agent and will be the valid and legally binding obligation

of the Warrante Agent, enforceable against such party in accordance with its terms; (4) at the time of the issuance and sale of any of the Securities, the terms of the Securities, and their issuance and sale, will have been established 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, and so as to comply with any requirement or restriction imposed by any court or governmental body having jurisdiction over the Company; and (5) that such documents will be governed by the laws of the State of New York.

Based upon the foregoing and in reliance thereon, and subject to the assumptions, comments, qualifications, limitations and exceptions set forth herein, we are of the opinion that:

1.    With respect to the Debt Securities, assuming the (a) taking of all necessary corporate action to authorize and approve the issuance and terms of the Debt Securities, the terms of the offering thereof and related matters approved by the Board of Directors of the Company, a duly constituted and acting committee of such board or duly authorized officers of the Company (such Board of Directors, committee or authorized officers being referred to herein as the “Board”) and (b) due execution, authentication, issuance and delivery of the Debt Securities upon payment of the consideration therefor provided for in the applicable definitive purchase, underwriting or similar agreement approved by the Board and otherwise in accordance with the provisions of the applicable Indenture, such Debt Securities will constitute valid and binding obligations of the Company, enforceable against the Company in accordance with their terms.

2.    With respect to the Common Stock, assuming the (a) taking by the Board of all necessary corporate action to authorize and approve the issuance of the Common Stock and (b) due issuance and delivery of the Common Stock, upon payment therefor in accordance with the applicable definitive purchase, underwriting or similar agreement approved by the Board, the Common Stock will be validly issued, fully paid and nonassessable.

3.    With respect to the Preferred Stock, assuming the (a) taking by the Board of all necessary corporate action to authorize and approve the issuance of the Preferred Stock, (b) due filing of the Certificate of Amendment to the Certificate of Incorporation of the Company, certificate of designation or other applicable document authorizing and establishing the terms of the Preferred Stock and (c) due issuance and delivery of the Preferred Stock, upon payment therefor in accordance with the applicable definitive purchase, underwriting or similar agreement approved by the Board, the Preferred Stock will be validly issued, fully paid and nonassessable.

4.    With respect to the Receipts, assuming the (a) taking of all necessary corporate action to authorize and approve the issuance and terms of the related Preferred Stock, (b) due filing of a Certificate of Amendment to the Certificate of Incorporation of the Company, certificate of designation or other applicable document authorizing and establishing the terms of the Preferred Stock, (c) terms of the Depositary Shares and of their issuance and sale have been duly established in conformity with the terms of a valid and legally binding Deposit Agreement conforming to the description thereof in the prospectus or prospectus supplement, (d) due issuance and delivery of the related Preferred Stock upon payment of the consideration therefor provided in the applicable definitive purchase, underwriting or similar agreement approved by the Board, and (e) due issuance and delivery of Receipts evidencing the Depositary Shares against the deposit of the Preferred Stock in accordance with the Deposit Agreement, such Receipts will be validly issued and will entitle the holders thereof to the rights specified in the Deposit Agreement.

5.    With respect to the Warrants, assuming the (a) taking of all necessary corporate action to authorize and approve the issuance and terms of the Warrants, the terms of the offering thereof and related matters and (b) due execution, countersignature, issuance and delivery of such Warrants, upon payment of the consideration for such Warrants provided for in the applicable definitive purchase, underwriting or similar agreement approved by the Board and otherwise in accordance with the provisions of the applicable Warrant Agreement, such Warrants will constitute valid and binding obligations of the Company, enforceable against the Company in accordance with their terms.

In addition to the assumptions, comments, qualifications, limitations and exceptions set forth above, the opinions set forth herein are further limited by, subject to and based upon the following assumptions, comments, qualifications, limitations and exceptions:

(a)    Our opinions herein reflect only the application of (i) applicable New York State law (excluding (A) all laws, rules and regulations of cities, counties and other political subdivisions of such State and (B) the securities, blue sky, environmental, employee benefit, pension, antitrust and tax laws of such State, as to which we express no opinion), (ii) the federal laws of the United States of America (excluding the federal securities, environmental, employee benefit, pension, tax, and antitrust laws, as to which we express no opinion), and (iii) to the extent required by the foregoing opinions, the General Corporation Law of the State of Delaware, including the statutory provisions and all applicable provisions of the Delaware Constitution and reported judicial decisions interpreting such laws. The opinions set forth herein are made as of the date hereof and are subject to, and may be limited by, future changes in factual matters, and we

undertake no duty to advise you of the same. The opinions expressed herein are based upon the law in effect (and published or otherwise generally available) on the date hereof, and we assume no obligation to revise or supplement these opinions should such law be changed by legislative action, judicial decision or otherwise. In rendering our opinions, we have not considered, and hereby disclaim any opinion as to, the application or impact of any laws, cases, decisions, rules or regulations of any other jurisdiction, court or administrative agency.

(b)    Our opinions contained herein are limited by (i) applicable bankruptcy, insolvency, reorganization, receivership, moratorium or similar laws affecting or relating to the rights and remedies of creditors generally including, without limitation, laws relating to fraudulent transfers or conveyances, preferences and equitable subordination, (ii) general principles of equity (regardless of whether considered in a proceeding in equity or at law), (iii) an implied covenant of good faith and fair dealing, (iv) requirements that a claim with respect to any Securities denominated other than in United States dollars (or a judgment denominated other than in United States dollars with respect to such a claim) be converted into United States dollars at a rate of exchange prevailing on a date determined pursuant to applicable law, and (v) governmental authority to limit, delay, or prohibit the making of payments outside the United States or in foreign or composite currency.

(c)    Our opinions are further subject to the effect of generally applicable rules of law arising from statutes, judicial and administrative decisions, and the rules and regulations of governmental authorities that: (i) limit or affect the enforcement of provisions of a contract that purport to require waiver of the obligations of good faith, fair dealing, diligence and reasonableness, (ii) limit the availability of a remedy under certain circumstances where another remedy has been elected, (iii) limit the enforceability of provisions releasing, exculpating, or exempting a party from, or requiring indemnification of a party for, liability for its own action or inaction, to the extent the action or inaction involves negligence, recklessness, willful misconduct or unlawful conduct, (iv) may, where less than all of the contract may be unenforceable, limit the enforceability of the balance of the contract to circumstances in which the unenforceable portion is not an essential part of the agreed exchange, and (v) govern and afford judicial discretion regarding the determination of damages and entitlement to attorneys’ fees.

(d)    We express no opinion as to:

(i)    the enforceability of any provision in any Indenture, Deposit Agreement, Warrant Agreement or other agreement purporting or attempting to (A) confer exclusive jurisdiction and/or venue upon certain courts or otherwise waive the defenses of forum non conveniens or improper venue, (B) confer subject matter jurisdiction on a court not having independent grounds therefor, (C) modify or waive the requirements for effective service of process for any action that may be brought, (D) waive the right of the Company or any other person to a trial by jury, (E) provide that remedies are cumulative or that decisions by a party are conclusive, (F) modify or waive the rights to notice, legal defenses, statutes of limitations and statutes of repose (including the tolling of the same) or other benefits that cannot be waived under applicable law, (G) govern choice of law or conflict of laws, or (H) provide for or grant a power of attorney; or

(ii)    the enforceability of (A) any rights to indemnification or contribution provided for in any Indenture, Deposit Agreement, Warrant Agreement or other agreement which are violative of public policy underlying any law, rule or regulation (including any Federal or state securities law, rule or regulation) or the legality of such rights, or (B) provisions in any Indenture, Deposit Agreement, Warrant Agreement or other agreement whose terms are left open for later resolution by the parties.

You have informed us that you intend to issue the Securities from time to time on a delayed or continuous basis, and this opinion letter is limited to the laws, including the rules and regulations, as in effect on the date hereof. We understand that prior to issuing any Securities you will afford us an opportunity to review the operative documents pursuant to which such Securities are to be issued (including the applicable prospectus supplement) and will file such supplement or amendment to this opinion letter (if any) as we may reasonably consider necessary or appropriate by reason of the terms of such Securities.

This opinion letter is being delivered by us solely for your benefit in connection with the filing of the Registration Statement with the Commission. We do not render any opinions except as set forth above. We hereby consent to the filing of this opinion letter as an exhibit to the Registration Statement and to the use of our name under the caption “Legal Matters” in the prospectus filed as a part thereof. We also consent to your filing copies of this opinion letter as an exhibit to the Registration Statement with agencies of such states as you deem necessary in the course of complying with the laws of such states regarding the offering and sale of the Securities. In giving this consent, we do not thereby concede that we are in the category of persons whose consent is required under Section 7 of the Act or the Rules and Regulations of the Commission thereunder.

Very truly yours,

/s/ Bryan Cave LLP