Exhibit 4.3

SECOND SUPPLEMENTAL INDENTURE

dated as of May 12, 2017

among

CHS/COMMUNITY HEALTH SYSTEMS, INC.,

the GUARANTORS party hereto,

REGIONS BANK,

as Trustee, Registrar and Paying Agent

and

CREDIT SUISSE AG,

as Collateral agent

to the

INDENTURE

dated as of March 16, 2017

between

CHS/COMMUNITY HEALTH SYSTEMS, INC.

and

REGIONS BANK,

as Trustee, Registrar and Paying Agent

Additional $900,000,000 6.250% Senior Secured Notes due 2023

This SECOND SUPPLEMENTAL INDENTURE (this “Second Supplemental Indenture”), dated as of May 12, 2017, among CHS/COMMUNITY HEALTH SYSTEMS, INC., a Delaware corporation (the “Issuer”), the GUARANTORS party hereto (the “Guarantors”), REGIONS BANK, an Alabama banking corporation (the “Trustee”), and CREDIT SUISSE AG, as collateral agent (the “Collateral Agent”).

RECITALS

WHEREAS, the Issuer and the Trustee have heretofore executed and delivered an Indenture, dated as of March 16, 2017 (the “Base Indenture”) and a First Supplemental Indenture, dated as of March 16, 2017 (the “First Supplemental Indenture” and, together with the Base Indenture, the “Indenture”), providing for the issuance on such date by the Issuer of $2,200,000,000 aggregate principal amount of the Issuer’s 6.250% Senior Secured Notes due 2023 (the “Initial Notes”);

WHEREAS, Section 2.1(a) of the First Supplemental Indenture provides, among other things, that the Issuer may issue, from time to time, in accordance with the provisions of the First Supplemental Indenture, Additional Notes having identical terms and conditions as the Initial Notes, other than, if applicable, the date from which interest will accrue;

WHEREAS, the Issuer has entered into that certain Underwriting Agreement, dated as of May 9, 2017, among the Issuer, the Guarantors and Credit Suisse Securities (USA) LLC, as representative of the underwriters, pursuant to which, among other things, on the date hereof, the Issuer is issuing $900,000,000 of 6.250% Senior Secured Notes due 2023 as Additional Notes (the “May 2017 Additional Notes”) as permitted by Section 2.1 of the First Supplemental Indenture;

WHEREAS, the Issuer intends by this Second Supplemental Indenture to create and provide for the issuance of the May 2017 Additional Notes as Additional Notes under the Indenture;

WHEREAS, pursuant to Section 9.1(7) of the First Supplemental Indenture, the Issuer, the Guarantors, the Trustee, and the Collateral Agent are authorized to execute and deliver this Second Supplemental Indenture to provide for the issuance of the Additional Notes under the Indenture without notice to or consent of any Holder; and

WHEREAS, all things necessary to make the May 2017 Additional Notes, when executed by the Issuer and authenticated and delivered by the Trustee, issued upon the terms and subject to the conditions set forth hereinafter and in the Indenture and delivered as provided in the Indenture against payment therefor, valid, binding and legal obligations of the Issuer according to their terms, and all actions required to be taken by the Issuer under the Indenture to make this Second Supplemental Indenture a valid, binding and legal agreement of the Issuer, have been done.

NOW, THEREFORE, in consideration of the foregoing and for other good and valuable consideration, the sufficiency and adequacy of which are hereby acknowledged, the parties hereto hereby agree as follows:

ARTICLE 1

DEFINITIONS AND INCORPORATION BY REFERENCE

Section 1.01 Definitions.

(a) All capitalized terms used herein and not otherwise defined herein shall have the meanings ascribed thereto in the Indenture.

(b) For all purposes of this Second Supplemental Indenture, except as otherwise herein expressly provided or unless the context otherwise requires: (i) the terms and expressions used herein shall have the same meanings as corresponding terms and expressions used in the Indenture; and (ii) the words “herein,” “hereof” and “hereby” and other words of similar import used in this Second Supplemental Indenture refer to this Second Supplemental Indenture as a whole and not to any particular section hereof.

ARTICLE 2

MAY 2017 ADDITIONAL NOTES

Section 2.01 Creation of the May 2017 Additional Notes. In accordance with Section 2.1(a) of the First Supplemental Indenture, the Issuer hereby creates the May 2017 Additional Notes as Additional Notes under the Indenture. The May 2017 Additional Notes shall be issued initially in an aggregate principal amount of $900,000,000 on the date hereof and will be issued at an issue price of 101.75% of the principal amount thereof plus accrued and unpaid interest from March 16, 2017. Interest on the May 2017 Additional Notes shall accrue from March 16, 2017.

Section 2.02 The Notes. The May 2017 Additional Notes initially will be issued in the form of Global Notes as follows:

(a) certificate number 006 (CUSIP No. 12543D AY6 / ISIN US12543DA Y67) in the aggregate principal amount of $500,000,000;

(b) certificate number 007 (CUSIP No. 12543D AY6 / ISIN US12543DA Y67) in the aggregate principal amount of $400,000,000.

ARTICLE 3

MISCELLANEOUS

Section 3.01 Ratification of the Base Indenture and the First Supplemental Indenture.

This Second Supplemental Indenture is executed and shall be constructed as an indenture supplement to the Indenture, and as supplemented and modified hereby, the Base Indenture and the First Supplemental Indenture are in all respects ratified and confirmed, and the Base Indenture, the First Supplemental Indenture and this Second Supplemental Indenture shall be read, taken and constructed as one and the same instrument.

Section 3.02 Trust Indenture Act Controls.

If and to the extent that any provision of this Second Supplemental Indenture limits, qualifies or conflicts with another provision which is required to be included in this Second Supplemental Indenture by the Trust Indenture Act, the provision required by the Trust Indenture Act shall control. Each Guarantor in addition to performing its obligations under its Note Guarantee shall perform such other obligations as may be imposed upon it with respect to this Second Supplemental Indenture under the Trust Indenture Act.

Section 3.03 Notices.

All notices and other communications shall be given as provided in the First Supplemental Indenture.

Section 3.04 Governing Law.

THIS SECOND SUPPLEMENTAL INDENTURE AND THE MAY 2017 ADDITIONAL NOTES SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

Section 3.05 Successors.

All agreements of the Issuer and each Guarantor in this Second Supplemental Indenture and the May 2017 Additional Notes shall bind their respective successors. All agreements of the Trustee and the Collateral Agent in this Second Supplemental Indenture shall bind their respective successors.

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Section 3.06 Multiple Originals.

The parties may sign any number of copies of this Second Supplemental Indenture. Each signed copy shall be an original, but all of them together represent the same agreement. One signed copy is enough to prove this Second Supplemental Indenture. The exchange of copies of this Second Supplemental Indenture and of signature pages by facsimile or PDF transmission shall constitute effective execution and delivery of this Second Supplemental Indenture as to the parties hereto and may be used in lieu of the original Second Supplemental Indenture for all purposes. Signatures of the parties hereto transmitted by facsimile or PDF shall be deemed to be their original signatures for all purposes.

Section 3.07 Headings.

The headings of the Articles and Sections of this Second Supplemental Indenture have been inserted for convenience of reference only, are not intended to be considered a part hereof and shall not modify or restrict any of the terms or provisions hereof.

Section 3.08 Trustee Not Responsible for Recitals.

Neither the Trustee nor the Collateral Agent make any representation or warranty as to the validity or sufficiency of this Second Supplemental Indenture or with respect to the recitals contained herein, all of which recitals are made solely by the other parties hereto.

[Signature page follows]

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IN WITNESS WHEREOF, the parties have caused this Second Supplemental Indenture to be duly executed as of the date first written above.

[Signature Page to Second Supplemental Indenture]

Acting on behalf of each of the Guarantors set forth above

[Signature Page to Second Supplemental Indenture]

Acting on behalf of each of the Guarantors set forth above

[Signature Page to Second Supplemental Indenture]

Acting on behalf of each of the Guarantors set forth above

[Signature Page to Second Supplemental Indenture]

Acting on behalf of each of the Guarantors set forth above

[Signature Page to Second Supplemental Indenture]

Acting on behalf of each of the Guarantors set forth above

[Signature Page to Second Supplemental Indenture]

[Signature Page to Second Supplemental Indenture]