In patients with primary cadaveric renal transplants and stable allograft function, we assessed the impact of tapering or discontinuing cyclosporine A (CsA) for financial reasons. Forty-two patients whose CsA was discontinued ("no-dose") and 29 patients whose CsA was tapered to 100 to 150 mg/d ("low-dose"; mean, 1.7 mg/kg/d) were examined. Results were compared with 70 age- and race-matched control patients maintained on at least 200 mg/d of CsA (mean, 3.9 mg/kg/d). Follow-up time for all patients averaged 55 +/- 18 months. Late acute rejection episodes occurred more frequently in no-dose than in low-dose (P = 0.017) or control (P = 0.001) patients. In the no-dose group, blacks experienced a greater number of late acute rejections than whites. These late acute rejections often coincided with the discontinuation of CsA and contributed to an increased rate of allograft loss in blacks in the no-dose group compared with black and white controls (P = 0.011). In contrast, no increase in late acute rejection episodes occurred in blacks tapered to low doses of CsA. Black patients who remained on low doses of CsA also exhibited a trend toward allograft survival that was intermediate between that of control and no-dose patients. In those patients who retained functional allografts, mean serum creatinine concentration did not differ between the study groups at the beginning and end of the follow-up period. These findings support continuance of CsA in black primary cadaveric renal transplant patients, even if dosages must be reduced to 100 to 150 mg/d.(ABSTRACT TRUNCATED AT 250 WORDS)