Objective/Background: Cytomegalovirus (CMV) reactivation remains a serious complication after allogeneic hematopoietic cell transplantation (HCT) occurring in approximately 60–70% of CMV-seropositive HCT recipients. CMV reactivation leads to adverse outcomes including end-organ damage, graft-versus-host disease, and graft failure. Methods: Ganciclovir was administered pretransplant at 5 mg/kg twice daily intravenously from the start of conditioning to Day T-2 to CMV-seropositive patients receiving their first allogeneic HCT. CMV DNA was monitored weekly until at least Day 100 posttransplant. Results: A total of 109 consecutive patients were treated, median age 57 (range 20–73) years. Of these, 36 (33%) patients had a CMV reactivation within the first 105 days posttransplant with a median time of reactivation of 52.5 (range 36–104) days posttransplant.The cumulative

incidence of CMV reactivation at Day 105 posttransplant was 33.1% (95% confidence interval: 24.4–42.0). One patient developed CMV disease. Conclusion: The use of pretransplant ganciclovir was associated with low incidence of CMV reactivation and disease. These data suggest that pretransplant ganciclovir with preemptive therapy for viral reactivation may be a useful strategy to reduce CMV reactivation. Future prospective trials are needed to compare strategies for CMV prophylaxis.