A 64-yr-old man presented with diabetes mellitus, proteinuria, hypertension and moderate renal dysfunction. Renal biopsy revealed diabetic glomerulosclerosis (diffuse lesion), IgA nephropathy and membranous nephropathy (stage 2). Both mesangial IgA and subepithelial IgG deposits were demonstrated by immunofluorescence and immunoelectron microscopy. Electron microscopic studies by immunogold method showed localization of IgA (diameter 15nm gold particles) within mesangial dense deposits and IgG (diameter 15nm gold particles) within subepithelial dense deposits. Overlapping IgA and membranous nephropathy was revealed in the same diabetic glomeruli with functional and biochemical alternations.