Ganciclovir reduces the incidence of CMV disease after kidney transplantation. The drug is given either intravenously (through a vein) twice a day or by mouth 3 times a day. Valganciclovir is converted to ganciclovir in the body and is absorbed into the bloodstream better than oral ganciclovir. In most transplant patients, a single daily dose of valganciclovir prevents CMV. Because of these advantages, some transplant patients are being given valganciclovir instead of ganciclovir to prevent CMV infection. However, the drug has not been studied in kidney and kidney transplant patients. This study will provide dosing information for this patient population.