A new immunosuppressive regimen combining anti-lymphocyte globulin, azathioprine,prednisone, and low doses of cyclosporine was used in 28 children aged 9 months to 17 years (mean 5.8 years) who recelved primary renal allografts between July 1, 1984, and September 25, 1986. After a mean follow-up of 17.3 months, the patient and graft survival is 100% (18 of 18) for mismatched related kidneys, and 90% (nine of 10) for cadaver kidneys. The single graft failure was the result of a death from technical complications. Serum creatinine concentration after transplantation ranged from 0.3 to 1.7 mg/dL (mean 0.85 mg/dL). The probability of a rejection episode in the first year was 45% and 60% for mismatched-related and cadaver kidneys, respectively. Cyclosporine nephrotoxicity was recognized in only one (3.7%) of 27 children, and was rapidly reversed after cyclosporine was discontinued. An initial group of nine children was weaned from cyclosporine therapy 6 to 12 months after transplantation, but two (22%) had rejection episodes. Our preliminary experience suggests that the use of a guadruple immunosuppressive regimen for both living related and cadaver renal transplants in children is associated with an improved graft function rate and a low incidence of complications.