In 1986, Weiss et al reported a group of patients with nephrotic syndrome, progressive chronic renal failure, and the histopathologic features of glomerular capillary collapse. Similar lesions are often described in human immunodeficiency virus (HIV) nephropathy. We evaluated 893 consecutive nontransplant renal biopsies performed in our department and the follow-up of the patients at our outpatient service. Sixteen specimens were identified with the pathological features of collapsing glomerulopathy (focal segmental or global glomerular capillary collapse and visceral epithelial cell hyperplasia), with no evidence of HIV infection and/or intravenous drug abuse. Their clinical characteristics were analyzed and compared with a group of 29 patients with noncollapsing focal segmental glomerulosclerosis (FSGS). The follow-up period of both patient groups was 5 +/- 1.46 years. The Kaplan-Meier life table method was used to present survival of the patients. The age of both groups was similar, 34 +/- 4 years (mean +/- standard error of the mean) for patients with collapsing glomerulopathy and 35 +/- 3 years for those with FSGS. The serum creatinine level was greater in patients with collapsing glomerulopathy (183 +/- 31 micromol/L) compared with those with FSGS (115 +/- 18 micromol/L), but the difference was not significant (P = 0.0504). The difference in proteinuria was not significant (P = 0.7668); it was 5.83 +/- 0.74 g/d in patients with collapsing glomerulopathy and 5.42 +/- 0.84 g/d in those with focal sclerosing glomerulonephritis. The difference in systolic (P = 0.4) and diastolic blood pressure (P = 0.556) was also not significant. Survival of the patients with collapsing glomerulopathy was worse than that of patients with FSGS (P = 0.025). Renal function survived 5 years in 40% of the patients with FSGS, but patients with collapsing glomerulopathy had no renal function survival. Our data suggest that idiopathic collapsing glomerulopathy is a distinct clinicopathologic entity with similar clinical features to focal sclerosing glomerulonephritis, but a worse prognosis and a rapidly progressive course toward end-stage renal disease.