Trademark Security Agreement

Exhibit 4.5

EXECUTION

Trademark Security Agreement

Trademark Security Agreement, dated as of May 7, 2010, by AMERICAN RENAL ASSOCIATES LLC (“Pledgor”), in favor of WILMINGTON TRUST FSB, in its capacity as Collateral Agent pursuant to the Indenture (in such capacity, the “Collateral Agent”).

W I T N E S S E T H:

WHEREAS, the Pledgor is party to a Security Agreement of even date herewith (as amended, amended and restated, supplemented or otherwise modified from time to time, the “Security Agreement”) in favor of the Collateral Agent pursuant to which the Pledgor is required to execute and deliver this Trademark Security Agreement;

NOW, THEREFORE, in consideration of the premises and to induce the Collateral Agent, for the benefit of the Holders of the Notes, to enter into the Indenture, the Pledgor hereby agrees with the Collateral Agent as follows:

SECTION 1. Defined Terms. Unless otherwise defined herein, terms defined in the Security Agreement and used herein have the meaning given to them in the Security Agreement.

SECTION 2. Grant of Security Interest in Trademark Collateral. Pledgor hereby pledges and grants to the Collateral Agent for the benefit of the Secured Parties a lien on and security interest in and to all of its right, title and interest in, to and under all the following Pledged Collateral of such Pledgor:

(a) Trademark registrations and applications of such Pledgor listed on Schedule I attached hereto;

(b) all Goodwill associated with such Trademarks; and

(c) all Proceeds of any and all of the foregoing (other than Excluded Property).

SECTION 3. Security Agreement. The security interest granted pursuant to this Trademark Security Agreement is granted in conjunction with the security interest granted to the Collateral Agent pursuant to the Security Agreement and Pledgor hereby acknowledges and affirms that the rights and remedies of the Collateral Agent with respect to the security interest in the Trademarks made and granted hereby are more fully set forth in the Security Agreement, the terms and provisions of which are incorporated by reference herein as if fully set forth herein. In the event that any provision of this Trademark Security Agreement is deemed to conflict with the Security Agreement, the provisions of the Security Agreement shall control.

SECTION 4. Intercreditor Agreement. Notwithstanding anything herein to the contrary, the Liens and security interests granted to the Collateral Agent pursuant to this Agreement and the exercise of any right or remedy by the Collateral Agent hereunder are subject to the terms of the Intercreditor Agreement and the Security Agreement. In the event of any conflict between the terms of the Intercreditor Agreement and the terms of this Agreement, the terms of the Intercreditor Agreement shall govern and control.

SECTION 5. Termination. Upon the payment in full of the Obligations and termination of the Security Agreement, the Collateral Agent shall execute, acknowledge, and deliver to the Pledgor an instrument in writing in recordable form releasing the collateral pledge, grant, assignment, lien and security interest in the Trademarks under this Trademark Security Agreement.

SECTION 6. Counterparts. This Trademark Security Agreement may be executed in any number of counterparts, all of which shall constitute one and the same instrument, and any party hereto may execute this Trademark Security Agreement by signing and delivering one or more counterparts.

SECTION 7. Governing Law. This Trademark Security Agreement and the transactions contemplated hereby, and all disputes between the parties under or relating to this Trademark Security Agreement or the facts or circumstances leading to its execution, whether in contract, tort or otherwise, shall be construed in accordance with and governed by the laws (including statutes of limitation) of the State of New York, without regard to conflicts of law principles that would require the application of the laws of another jurisdiction.

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IN WITNESS WHEREOF, Pledgor has caused this Trademark Security Agreement to be executed and delivered by its duly authorized officer as of the date first set forth above.

SCHEDULE I

to

TRADEMARK SECURITY AGREEMENT

UNITED STATES TRADEMARK REGISTRATIONS AND TRADEMARK

APPLICATIONS

Registrations:

Applications:

None.