Forty seven renal allografts performed over a period of 12 years in 43 recipients with chronic renal failure due to biopsy-proved focal glomerulosclerosis (FGS, 5.34% from 888 cadaveric renal transplantations) were reviewed. Recurrence of the disease was suspected in 14 grafts (29.8%) on the basis of immediate proteinuria, but recurrence of FGS lesions was demonstrated in only 7 patients. The remaining 7 patients had minimal-change nephropathy or mesangial hyperplasia. The duration of renal disease before transplantation was a clear predictive risk factor of FGS recurrence, and mesangial hyperplasia in the native kidneys was associated with 50% risk of FGS recurrence. Some reports have suggested that plasma exchange may be beneficial in the treatment of FGS recurrence. Our experience, in 9 patients, indicates that plasma exchange initiated early in the course of recurrent proteinuria leads to transient but significant disappearance (2 cases) or decrease (5 cases) of proteinuria, with a return to pre—plasma exchange levels within 2 weeks after the end of treatment. In 2 cases, there was no beneficial effect on proteinuria. Plasma exchange efficacy was correlated with proteinuria levels relative to disease severity. Although plasma exchange does not seem to improve the outcome of FGS recurrence, it demonstrates the possible presence of circulating factor (s) and argues for the characterization of humoral mediator (s).