Exhibit 99.18

LaSalle Bank	LaSalle Bank N.A.,
ABN AMRO	135 S. LaSalle Street
	Chicago, IL 60603
	312/904-8659
	Facsimile: 312/904-6457
	george.kumis@abnamro .com
	George L. Kumis
	Senior Vice President
	Commercial Lending: Healthcare Industry

Acceptance of Request for Extension

December 22, 2006

Aetna Inc,
151 Farmington Avenue
Hartford, CT 06156

Re: Amended and Restated Five-Year Credit Agreement dated as of January 20, 2006 (the “Credit Agreement”)

Attention: Alfred P. Quirk, Vice President, Finance and Treasurer

Dear Al:

We have received your Extension Request, dated December 5, 2006, and pursuant to Section 2.06(c) (Maturity of Loans) of the above-referenced Credit Agreement, we hereby agree to the extension set forth in such request. Upon the effectiveness of the Extension Request in accordance with Section 2.06(c) of the Credit Agreement, the new Maturity Date will be January 20, 2012.

We have made a notation of this extension on the Schedule of Loans, Payments of Principal attached to our Syndicated Note(s).

Very truly yours,
LASALLE BANK NATIONAL ASSOCIATION
By:	/s/ George L. Kumis
	Name: George L. Kumis
	Title: Senior Vice President