Cyclosporin A significantly improves patient and graft survival as compared with the conventional corticosteroid-azathioprine treatment. However, the results are the same, or even worse, when the cyclosporin A-corticosteroid regimen is compared with the corticosteroid-azathioprine-antilymphocyte globulin regimen. The authors have investigated a prednisone-azathioprine-low dose cyclosporin A combination in 46 high risk patients from a series of 117 renal transplantations performed in 1983. The actuarial patient and graft survival rates were as good as, but not better than, those obtained in 1982 in 106 patients treated with the conventional regimen which includes antilymphocyte globulin; they were 96.5% vs 98% and 85.5% vs 84% respectively at 6 months; 96.5% vs 98% and 83.5% vs 84% respectively at 12 months. The low dosage utilized (8 mg/kg instead of the usual 14-17 mg/kg) avoided virtually all the extrarenal side-effects of cyclosporin A, but not its nephrotoxicity. The theoretical risk of excessive immunosuppression was not confirmed by our study. Since cyclosporin A is very expensive, other therapeutic methods for optimal usage of that drug should be investigated.