To evaluate the rate of recurrence of focal segmental glomerulosclerosis (FSGS) in renal transplant patients treated with cyclosporine, we reviewed the outcome of 25 renal Tx performed in 24 patients who had FSGS as their original renal disease. After Tx, 6 patients were treated with steroids and azathioprine (follow-up: 42 +/- 34 months) and 19 with CsA (follow-up: 30 +/- 31 months). Two of 6 Aza treated patients (33%) developed recurrence of FSGS and nephrotic syndrome (NS). Both patients lost their graft because of FSGS 24 and 25 months after Tx. Ten of 19 patients (55%) given CsA showed recurrence of FSGS; one of them had had recurrence in the first graft treated with Aza. One patient lost his graft a few weeks after Tx because of acute rejection and 3 lost their graft because of FSGS 4-28 months after NS developed. One patient with NS died from pneumonia 14 months after Tx when his plasma creatinine was 2.7 mg/dl. Three other patients now have NS and plasma creatinine between 1.9 and 2.4 mg/dl 15-37 months after Tx. The last two patients have NS and normal renal function 10 and 31 months after Tx. In both groups, most patients developed NS within the first week after Tx. The patients with recurrence, given Aza or CsA, tended to be younger at the onset of the disease and to have a shorter duration of the disease, when compared with those without recurrence, but the differences were not statistically significant. In our experience neither CsA nor Aza showed any effect on the outcome of FSGS recurring in the graft.