it is unknown whether the addition of mycophenolate mofetil (MMF) to cyclosporine (CsA) and prednisone after renal transplantation (RTx) allows for a reduced dose of CsA, to minimize the incidence of CsA-related side effects and to reduce costs. Therefore, 313 renal allograft recipients were randomized for treatment with MMF (1000 mg twice a day), prednisone, and either conventional- or low-dose CsA during the first 3 mo after RTx. The target trough levels were 300 and 150 ng/ml, respectively, during the first 3 mo and 150 ng/ml in both groups thereafter. A total of 313 patients were included: 161 patients received a conventional dose and 152 received a low dose of CsA. During the first 6 mo after RTx, graft failure or patient death occurred in 19 of 161 patients (12%) in the conventional-dose group and in 11 of 152 patients (7%) in the low-dose group (not significant). Biopsy-proven acute rejection occurred in 36 of 161 patients (22%) in the conventional dose group and in 29 of 152 patients (19%) in the low-dose group (not significant). The incidence of delayed graft function was similar in both groups (31 of 161 [19%] versus 28 of 152 [18%]; not significant). Serum creatinine did not differ between the conventional- and the low-dose groups: 151 +/- 56 mu mol/L versus 142 +/- 49 mu mol/L at 3 mo and 141 +/- 60 mu mol/L versus 136 +/- 49 mu mol/L at 6 mo. There were no differences between the groups regarding BP, lipid metabolism, and infectious complications. In the low-dose group, an estimated $500 per patient was saved on the costs of CsA. In conclusion, the addition of MMF to CsA and prednisone after RTx allows the use of a lower-than-conventional dose of CsA, without increasing the risk of rejection.