Exhibit 5.1

Simpson Thacher & Bartlett llp
425 Lexington Avenue
New York, N.Y. 10017-3954
(212) 455-2000
Facsimile (212) 455-2502

September 21, 2011

HCA Holdings, Inc.
One Park Plaza
Nashville, TN 37203

Ladies and Gentlemen:

     We have acted as counsel to HCA Holdings, Inc., a Delaware corporation (the “Company”), in connection with the Registration Statement on Form S-4 (the “Registration Statement”) filed by the Company with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended, relating to the issuance by the Company of up to $1,525,000,000 aggregate principal amount of 7³/4% Senior Notes due 2021 (the “Exchange Notes”). The Exchange Notes will be issued under an indenture dated as of November 23, 2010 (the “Indenture”) among the Company, Law Debenture Trust Company of New York, as trustee (the “Trustee”), and Deutsche Bank Trust Company Americas, as paying agent, registrar and transfer agent (the “Paying Agent”). The Company will offer the Exchange Notes in exchange (the “Exchange”) for $1,525,000,000 aggregate principal amount of its outstanding 7³/4% Senior Notes due 2021.

     We have examined the Registration Statement and the Indenture, which has been filed with the Commission as an exhibit to the Registration Statement. We also have examined the originals, or duplicates or certified or conformed copies, of such records, agreements, documents and other instruments and have made such other investigations as we have deemed relevant and necessary in connection with the opinion hereinafter set forth. As to questions of fact material to this opinion, we have relied upon certificates or comparable documents of public officials and of officers and representatives of the Company.

     In rendering the opinion set forth below, 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 original documents of all documents submitted to us as duplicates or certified or conformed copies and the authenticity of the originals of such latter documents. We also have assumed that the Indenture is the valid and legally binding obligations of the Trustee and the Paying Agent.

     Based upon the foregoing, and subject to the qualifications, assumptions and limitations stated herein, we are of the opinion that when the Exchange Notes have been duly executed, authenticated, issued and delivered in accordance with the provisions of the Indenture upon the Exchange, the Exchange Notes will constitute valid and legally binding obligations of the Company enforceable against the Company in accordance with their terms.

     Our opinion set forth above is subject to (i) the effects of bankruptcy, insolvency, fraudulent conveyance, reorganization, moratorium and other similar laws relating to or affecting creditors’ rights generally, (ii) general equitable principles (whether considered in a proceeding in equity or at law) and (iii) an implied covenant of good faith and fair dealing.

     We do not express any opinion herein concerning any law other than the law of the State of New York, the federal law of the United States and the Delaware General Corporation Law (including the statutory provisions, all applicable provisions of the Delaware Constitution and reported judicial decisions interpreting the foregoing).

     We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the Registration Statement and to the use of our name under the caption “Legal Matters” in the Prospectus included in the Registration Statement.

Very truly yours,

/s/ Simpson Thacher & Bartlett LLP
SIMPSON THACHER & BARTLETT LLP