SUPPLEMENT NO. 1 TO GUARANTY

Exhibit 10.6

SUPPLEMENT NO. 1 TO GUARANTY

SUPPLEMENT NO. 1 dated as of December     16     , 2010, to the Guaranty dated as of June 29, 2007, among ASC ACQUISITION, LLC, a Delaware limited liability company (“Holdings”), SURGERY CENTERS MERGER SUB LLC, a Delaware limited liability company (“Merger Sub”) to be merged with and into SURGICAL CARE AFFILIATES, LLC, a Delaware limited liability company (“SCA”), certain subsidiaries of SCA from time to time party hereto (collectively, “Subsidiaries” and, individually, “Subsidiary”), and JPMORGAN CHASE BANK, N.A., as Administrative Agent (as defined below).

A. Reference is made to (i) the Credit Agreement dated as of June 29, 2007 (as amended, supplemented or otherwise modified from time to time, the “Credit Agreement”), among the Borrower (as defined below), Holdings, JPMorgan Chase Bank, N.A., as Administrative Agent, Swing Line Lender, and L/C Issuer, each lender from time to time party thereto (collectively, the “Lenders” and individually, a “Lender”), X.X. Xxxxxx Securities Inc. and Xxxxxxx Sachs Credit Partners L.P., as joint lead arrangers and joint bookrunners, Xxxxxxx Xxxxx Credit Partners L.P., as syndication agent, and General Electric Capital Corporation, Natixis and the Royal Bank of Scotland plc, as documentation agents, (ii) each Secured Hedge Agreement (as defined in the Credit Agreement), and (iii) the Cash Management Obligations (as defined in the Credit Agreement).

B. Capitalized terms used herein and not otherwise defined herein shall have the meanings assigned to such terms in the Credit Agreement.

C. The Guarantors have entered into the Guaranty in order to induce (i) the Lenders to make Loans and the L/C Issuers to issue Letters of Credit, (ii) the Hedge Banks to enter into and/or maintain Secured Hedge Agreements and (iii) the Cash Management Banks to provide Cash Management Services. Section 4.11 of the Guaranty provides that additional wholly-owned Domestic Material Subsidiaries of the Borrower may become Guarantors under the Guaranty by execution and delivery of an instrument in the form of this Supplement. The undersigned wholly-owned Domestic Material Subsidiary (the “New Subsidiary”) is executing this Supplement in accordance with the requirements of the Credit Agreement to become a Guarantor under the Guaranty in order to induce (A) the Lenders to make additional Loans and the L/C Issuers to issue additional Letters of Credit, (B) the Hedge Banks to enter into and/or maintain Secured Hedge Agreements and (C) the Cash Management Banks to provide Cash Management Services and as consideration for (x) Loans previously made and Letters of Credit previously issued, (y) Secured Hedge Agreements previously entered into and/or maintained and (z) Cash Management Services previously provided.

Accordingly, the Administrative Agent and the New Subsidiary agree as follows:

SECTION 1. In accordance with Section 4.11 of the Guaranty, the New Subsidiary by its signature below becomes a Guarantor under the Guaranty with the same force and effect as if originally named therein as a Guarantor and the New Subsidiary hereby (a) agrees to all the terms and provisions of the Guaranty applicable to it as a Guarantor thereunder and (b) represents and warrants that the representations and warranties made by it as a Guarantor thereunder are true and correct on and as of the date hereof. In furtherance of the foregoing, the

New Subsidiary, as security for the payment and performance in full of the Obligations does hereby, for the benefit of the Secured Parties, their successors and assigns, irrevocably, absolutely and unconditionally guaranty, jointly with the other Guarantors and severally, the due and punctual payment and performance of the Obligations. Each reference to a “Guarantor” in the Guaranty shall be deemed to include the New Subsidiary. The Guaranty is hereby incorporated herein by reference.

SECTION 2. The New Subsidiary represents and warrants to the Administrative Agent and the Secured Parties that this Supplement has been duly authorized, executed and delivered by it and constitutes its legal, valid and binding obligation, enforceable against it in accordance with its terms, except as such enforceability may be limited by Debtor Relief Laws and by general principles of equity.

SECTION 3. This Supplement may be executed in counterparts (and by different parties hereto on different counterparts), each of which shall constitute an original, but all of which when taken together shall constitute a single contract. This Supplement shall become effective when the Administrative Agent shall have received a counterpart of this Supplement that bears the signature of the New Subsidiary, and the Administrative Agent has executed a counterpart hereof. Delivery of an executed signature page to this Supplement by facsimile transmission or other electronic communication shall be as effective as delivery of a manually signed counterpart of this Supplement.

SECTION 4. Except as expressly supplemented hereby, the Guaranty shall remain in full force and effect.

SECTION 5. THIS SUPPLEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.

SECTION 6. If any provision contained in this Supplement is held to be invalid, illegal or unenforceable, the legality, validity, and enforceability of the remaining provisions contained herein and in the Guaranty shall not be affected or impaired thereby. The invalidity of a provision in a particular jurisdiction shall not invalidate or render unenforceable such provision in any other jurisdiction.

SECTION 7. All communications and notices hereunder shall be in writing and given as provided in Section 4.01 of the Guaranty.

SECTION 8. The New Subsidiary agrees to reimburse the Administrative Agent for its reasonable out-of-pocket expenses in connection with the execution and delivery of this Supplement, including the reasonable fees, other charges and disbursements of counsel for the Administrative Agent.

[SIGNATURES ON THE FOLLOWING PAGE]

2

IN WITNESS WHEREOF, the New Subsidiary and the Administrative Agent have duly executed this Supplement to the Guaranty as of the day and year first above written.

SCA SURGERY HOLDINGS, LLC
By:		/s/ Xxxxxxx X. Xxxxxx, Xx.
		Name: Xxxxxxx X. Xxxxxx, Xx.
		Title: Vice President and Secretary
Jurisdiction of Formation: Delaware Organizational Identification Number: # 4545056 Address of Chief Executive Office: 0000 Xxxxxxxxxx Xxxxxxxx Xxxxx 000 Xxxxxxxxxx, XX 00000 JPMORGAN CHASE BANK, NA.,     as Administrative Agent
By:
		Name:
		Title:

Signature Page for Supplement No. 1 to Guaranty

IN WITNESS WHEREOF, the New Subsidiary and the Administrative Agent have duly executed this Supplement to the Guaranty as of the day and year first above written.

SCA SURGERY HOLDINGS, LLC
By:
		Name: Xxxxxxx X. Xxxxxx, Xx.
		Title: Vice President and Secretary
Jurisdiction of Formation: Delaware Organizational Identification Number: # 4545056 Address Of Chief Executive Office: 0000 Xxxxxxxxxx Xxxxxxxx Xxxxx 000 Xxxxxxxxxx, XX 00000 JPMORGAN CHASE BANK, NA.,     as Administrative Agent
By:		/s/ Xxxx XxxXxx
		Name: Xxxx XxxXxx
		Title: Executive Director

Signature Page for Supplement No. 1 to Guaranty