Oral ganciclovir prophylaxis and intravenous preemptive therapy are competitive approaches to prevent cytomegalovirus (CMV) disease after renal transplantation. This trial compared efficacy, safety and long-term graft outcome in 148 renal graft recipients randomized to ganciclovir prophylaxis (N = 74) or preemptive therapy (N = 74). Hierarchical testing revealed (i) patients with CMV infection had more severe periods of impaired graft function (creatinine clearance max−min 25.0 ± 14.2 mL/min vs. 18.1 ± 12.5 mL/min for patients without CMV infection; p = 0.02),(ii) prophylaxis reduced CMV infection by 65% (13 vs. 33 patients; p < 0.0001) but (iii) creatinine clearance at 12 months was comparable for both regimes (54.0 ± 24.9 vs. 53.1 ± 23.7 mL/min; p = 0.92). No major safety issues were observed, and patient survival at 12 months was similar in both groups (5 In conclusion, it appears that routine oral prophylaxis may improve long-term graft survival for most renal transplant patients. Preemptive therapy can be considered in low risk patients in combination with adequate CMV monitoring. †V.K. and L.F. both contributed equally to this work.