OBJECTIVES:  Cytomegalovirus (CMV) disease can severely impact patient outcomes and costs associated with kidney transplant. The IMPACT study has shown that kidney transplant patients significantly benefit from extending valganciclovir prophylaxis from 100 to 200 days. The objective of this study was to determine the cost-effectiveness of valganciclovir 200 day prophylaxis compared to 100 days in kidney transplant patients at high-risk for developing CMV disease. METHODS:  A Markov model was developed to capture time spent by patients in various health states, which included: CMV, No-CMV, Acute Rejection, Graft Failure, Dialysis and Death.  Results were reported as incremental cost per additional quality adjusted life-years (QALY) gained, over a 10-year period. Transition probabilities for the first year were derived from the IMPACT study.  Data beyond the first year were derived from the published literature and baseline mortality rate was determined from the Canadian Organ Replacement Register. The base case analysis focused on direct medical costs only from the perspective of the Ministry of Health (MoH).  A second analysis was conducted from the societal perspective. Cost data were obtained from a variety of sources and reported as 2010 Canadian Dollars. A 5% discount rate was applied to both costs and patient outcomes. Multiple sensitivity analyses were undertaken to test the robustness of the model. RESULTS:  From the MoH perspective valganciclovir 200 days prophylaxis is cost-effective when compared to 100 days with an incremental cost-utility ratio (ICUR) of $34,818 per additional QALY gained. The cost-effectiveness is improved from the societal perspective, with an ICUR of $32,571 per additional QALY gained. Results were robust over a wide range of sensitivity analyses tested. CONCLUSIONS:  Valganciclovir 200 days is a cost-effective prophylaxis strategy in kidney transplant patients at high-risk of developing CMV when compared to valganciclovir 100 days.