Fifty-eight consecutive paediatric recipients of 65 renal transplants were prospectively studied for up to 72 months for evidence of cytomegalovirus (CMV) infection. Blood, urine and saliva were screened for CMV pre transplant and then weekly for the first 6 weeks, and monthly thereafter, by conventional cell culture and by detection of early antigen fluorescent foci. Donor CMV serostatus was available in 51 cases. All patients received triple therapy as immunosuppression and none had CMV prophylaxis. Twenty-six episodes of CMV infection (40% of transplants) and 10 of CMV disease (15%) were identified. Donor CMV seropositivity, regardless of recipient CMV serostatus, was significantly associated with CMV infection (P = 0.04). First CMV excretion was significantly earlier in patients who subsequently became symptomatic than in those who did not (P = 0.04), and a positive blood culture was significantly associated with CMV disease (P = 0.04). We found no association between extra anti-rejection treatment or recipient's age and CMV infection or disease. CMV disease had no influence on renal function as assessed by glomerular filtration rate at 6, 12 and 24 months post transplant, nor on graft loss. CMV disease was fatal in 1 patient. We conclude that trials of CMV prophylactic agents are indicated, particularly in recipients of CMV seropositive grafts. A positive blood culture should lead to consideration of anti-CMV therapy.