The effect of race upon renal allograft survival is controversial. Between 1981 and 1987, at Vanderbilt University Medical Center, 448 patients (75 black, 373 white) received azathioprine, 3 mg/kg daily; prednisone, 30 mg daily; and intravenous antithymocyte sera, 0.2 mL/kg/day for 14 days, after transplantation. Prednisone doses were decreased gradually to 10 mg daily within 6 months of transplantation. Azathioprine was maintained at doses of 2 to 3 mg/kg/daily; lower doses were administered if significant myelosuppression occurred. One-year graft survival was 72% and 85% among black and white recipients, respectively (P less than .01). Two hundred thirty-six patients have been treated with azathioprine (3 mg/kg initially tapered during the first week to 1.5 to 2 mg/kg); prednisone, 30 mg daily; and cyclosporine, 10 mg/kg per day. Cyclosporine therapy was begun after recipient serum creatinine levels had decreased below 3 mg/dL. Before therapy was initiated and until levels of cyclosporine were maintained between 150 and 200 ng/mL (whole blood), antithymocyte serum was administered. This immunosuppressive protocol resulted in 1-year graft survival of 90% and 87% in black and white recipients, respectively. Not only was graft loss markedly reduced, but the interracial difference noted before the use of cyclosporine was no longer evident. The type of immunosuppressive therapy used clearly affected 1-year allograft survival among black recipients. The combination of azathioprine, cyclosporine, and prednisone resulted in improved graft survival overall, but had the most significant effect among blacks.