In the present study, urinary tumor necrosis factor-α (TNF) levels in nonproliferative glomerulopathies [minimal change disease (n = 4), focal glomerulosclerosis (n = 4), membranous glomerulonephritis (GN) (n = 1), and in patients with chronic glomerulopathies (n = 4)] were compared to proliferative ones [a rapidly progressive GN patient and 8 patients with mesangial proliferative GN and membranoproliferative GN (MPGN) who had clinically active disease]. The mean urine TNF levels of the proliferative group were significantly higher than both the nonproliferative GN and 4 controls, whereas the mean value of the nonproliferative group was not significantly different than the controls. The urine TNF levels in 4 MPGN patients with chronic disease and in 2 who entered remission were also very low. In the patients with active renal disease and cellular proliferation there were significant correlations between the urinary TNF levels and both proteinuria and the clinical activity scores. We suggest that in human proliferative glomerulopathies TNF may be implicated in the glomerular inflammation