The influence of the cytomegalovirus (CMV) serostatus of blood and kidney donors on patient and graft survival was studied prospectively in 73 cadaveric renal graft recipients. Six out of 12 (50%) CMV seronegative recipients receiving a kidney from a CMV seropositive donor developed CMV disease, in contrast to none of 7 CMV seronegative donor/recipient combinations. Transmission of CMV with blood products to seronegative recipients was not observed in this study. A poor graft survival of 41% 3 years after transplantation was found in CMV seronegative recipients with CMV seropositive allograft donors, compared with an actuarial 3 year graft survival of 72% in the 7 CMV seronegative donor/recipient combinations. Six patients with graft failure had a CMV infection. This study, in accordance with other studies, suggests that selection of CMV seronegative renal allograft donors for CMV seronegative recipients will improve graft survival.