Skin-muscle and kidney biopsy specimens were obtained from 43 patients with glomerulonephritis and from 5 normal subjects. 14 of the 43 patients had mesangial IgA nephropathy and in 12 the immunofluorescence study of skin-muscle biopsy showed IgA deposits. Ultrastructural research performed on 4 of these patients showed some electron-dense deposits on the walls of the muscular capillaries or in the perivascular connective tissue which could represent the immune aggregates. The remaining 29 patients had nonsystemic chronic glomerulonephritis with various immune deposits; only in 7 of these patients was the immunofluorescence study positive. The said study suggests that immunofluorescence examination of skin-muscle biopsy specimens could be diagnostically important.