Among 1168 patients in whom clinical data and light microscopic, immunofluorescence and electron microscopic findings of renal biopsies were available, 329 had minor glomerular abnormalities. These 329 cases included 38 with glomerular minimal change (MC), 32 with glomerular minor lesion, 143 with mild mesangioproliferative GN, 14 with mild mesangioproliferative IgM nephropathy, 4 with C1q nephropathy, 37 with IgA nephropathy, 12 with Henoch-Schönlein purpura GN, 17 with lupus nephritis, 16 with early stage membranous nephropathy (eMN), 4 with Alport's syndrome (ALS), 7 with thin basement membrane nephropathy (TMN) and 5 with nonglomerular haematuria. Their histologic appearances were nearly normal, and immunofluorescence was negative or mild positive. But electron microscopic appearances were diagnostic. Electron microscopy is the only diagnostic method for MC, ALS, TMN and eMN.