In this retrospective study we report the outcome of 59 adults with idiopathic focal-segmental glomerulosclerosis (FSGS) and nephrotic syndrome (NS) treated with corticosteroids and/or immunosuppressive drugs. Twenty-seven patients were initially treated with corticosteroids alone for 9.3 +/- 8 months; nineteen patients received corticosteroids and immunosuppressive agents associated or every other month for 5.5 +/- 4 months; thirteen patients received either azathioprine or cyclophosphamide alone for 25 +/- 27 months. At the end of a mean follow-up of 75 +/- 51 months, 35 patients (60%) were in complete (CR) or partial (PR) remission, 6 (10%) were stable and 18 (30%) had either chronic renal failure (CRF) or end-stage renal failure (ESRF). Out of 36 patients (61%) initially responsive to therapy, 30 (83%) obtained CR, 4 (11%) PR, one (2.7%) developed CRF and one (2.7%) ESRF. Only 10 of the responders (28%) attained remission within 8 weeks of treatment. Out of the 23 (39%) patients originally resistant to therapy, only one (4%) had CR, 6 (26%) remained unchanged, 6 (26%) developed CRF and 10 (43%) ESRF. The presence at initial renal biopsy of interstitial fibrosis was the only feature which could predict a poor renal outcome. These data show that prolonged treatment of FSGS can obtain sustained remission of the disease and improved renal survival in a consistent proportion of adult patients which would be considered refractory to a two-month course with corticosteroids.