Renal transplantation (11 cadaveric and 1 living-related donor) was performed in 12 pediatric recipients (mean age 10.8 years) under FK-506 immunosuppression in combination with prednisone therapy. At a mean followup of 6.1 months, patient and graft survival rates were 100% and 92%, respectively. The only graft loss was due to the recurrent hemolytic uremic syndrome 4 days after transplantation. In the functioning grafts the mean serum creatinine is 1.59 +/- 1.27 mg./dl. and the mean blood urea nitrogen is 36.3 +/- 24.6 mg./dl. Three patients take no prednisone, 5 are receiving 0.15 to 0.25 mg./kg. per day and 3 are taking 0.35 to 0.5 mg./kg. per day. There was a total of 8 rejection episodes in 5 patients. All rejection episodes were successfully reversed. Complications of transplantation included an episode of seizures in 1 patient, cytomegalovirus infection in 1 and steroid-induced diabetes mellitus in 1. Since pediatric transplant recipients are a group in whom the reduction or elimination of steroids is highly desirable, FK-506 immunosuppression may be particularly suited for use in this population.