The influence of cyclosporine pharmacokinetic parameters on clinical events and outcome after transplantation was studied in 100 renal transplant recipients who underwent a pre-as well as posttransplant CsA pharmacokinetic evaluation. Among the patients, 30 were black and 50 were white. Black recipients had significantly lower bioavailability (F) pre-as well as posttransplantation than white recipients, the post-transplant mean F values being 25.8±9.0% and 38.1→ 16.7%, respectively (Poral) were significantly higher in patients who had acute rejection than in those who did not, with CL mean values of 425±141 ml/min and 359±131 ml/min, respectively (Poral higher in patients who eventually lost their grafts than in those who did not, the mean F values being 26.5±12.8% and 38.7± 17.5%, respectively (Poral decreased during the first 3 months after transplantation (P<0.0001), but it was stable thereafter. Neither the bioavailability nor the clearance of CsA showed a correlation with administered dose. These results indicate that certain recipient groups, such as black patients, and individuals with rapid CL, may benefit from larger CsA doses and/or shorter dosage intervals, in order to compensate for these interpatient variabilities.