UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549-0404 DIVISION OF CORPORATION FINANCE Mail Stop 3561 April 21, 2006 Mr. Mark H. Collin Unitil Corporation 6 Liberty Lane West Hampton, NH 03842-1720 Re: Unitil Corporation Form 10-K for the fiscal year ended December 31, 2005 Filed February 22, 2006 File No. 001-08858 Dear Mr. Collin: We have completed our review of your Form 10-K and have no further comments at this time. Sincerely, James Allegretto Senior Assistant Chief Accountant