Despite improving overall results of pediatric renal transplantation children under 5 years of age remain a high-risk group with poorer outcomes often because of a higher rate of surgical complications. This retrospective report details a 12-year experience at a single center and examines the outcome in this high-risk group of patients. We reviewed the medical records of 21 children under 5 years of age who received renal transplantation at Loma Linda University Medical Center between July 1988 and August 2000. The patients were evaluated regularly by the same pediatric nephrologist throughout the study period at our outpatient clinic. Mean recipient age was 3 +/- 1.2 (range 2-5) years; weight at transplantation was 13.3 +/- 5.4 kg. Ten (48%) patients received living related donor (LRD) kidneys and 11 (52%) received cadaver (CAD) kidneys. Mean donor ages for CAD and LRD were 14.4 +/- 10 years and 26.6 +/- 4.9 years, respectively. The mean cold ischemia time (CAD only) was 23.3 +/- 10.6 hours. Renal dysplasia (n = 8) and obstructive uropathy (n = 5) were the most common primary diagnoses. Maintenance immunosuppression consisted of Azathioprine or mycophenolate mofetil (MMF), cyclosporine or tacrolimus and prednisone. Mean follow-up was 80.1 +/- 51.4 months. Twelve (57%) grafts have a follow-up >5 years. Patient survival was 100 per cent. Overall graft survival at one, 3, 5, and 10 years were 95, 95, 88, and 88 per cent respectively. Graft survival for LRD recipients was 100 per cent. No graft was lost as a result of a technical problem or vascular thrombosis. One graft each was lost because of delayed graft function complicated by severe cytomegalovirus infection and chronic rejection. At one year the mean serum creatinine was 0.6 +/- 0.2 mg/dL with a mean calculated glomerular filtration rate of 93 +/- 32 mL/min. All 17 children who are now of school age are attending school. We conclude that excellent rehabilitation and superior long-term patient and graft survival can be achieved with renal transplantation in children of this age group with the use of good surgical techniques and close follow-up.