In order to clarify considerable alterations of the extracellular matrix components in various renal diseases, monoclonal antibodies against type IV collagen (IV col), 200-KD laminin (200-KD Lam), 400-KD laminin (400-KD Lam) and heparan sulfate proteoglycan (HSPG) were applied to 142 renal biopsy specimens for the indirect immunofluorescence. These subjects included 5 cases with 1 hour specimen in the transplanted kidney, 32 minimal change nephrotic syndrome (MCNS), 30 mesangial proliferative glomerulonephritis (PGN), 2 focal segmental glomerulosclerosis (FGS), 21 membranous nephropathy (MN), 9 membranoproliferative glomerulonephritis (MPGN), 2 poststreptococcal acute glomerulonephritis (PSAGN), 13 diabetic nephropathy (DN), 16 lupus nephritis (LN), 9 diffuse sclerosing glomerulonephritis (DSGN), 2 amyloid kidney and 1 granulomatous nephropathy in sarcoidosis. In the transplanted kidney, the staining intensity of IV col was stronger than that of 200-KD Lam, 400-KD Lam and HSPG in general. IV col was predominantly distributed throughout the mesangium area and less along the glomerular basement membrane (GBM). The positive stainings with 200-KD Lam along the GBM and that with 400-KD Lam in the mesangium area were weakly recognized. HSPG was mainly detected along the GBM in the linear fashion. In MCNS, the distribution of the extracellular matrix components was mostly identical to that in the transplanted kidney. In the group of the glomerulonephritis showed the proliferations of mesangial cells, such as PGN and MPGN, the staining intensity of both IV col and 400-KD Lam, particularly in the latter, was remarkably increased in the sclerotic lesions. In MN, the thickened GBM was strongly stained with both IV col and 200-KD Lam, and the stainings of 200-KD Lam were more intensive. And still more, by the double labelling method performed for the couple of IV col and immunoglobulins, the correlation between glomerular capillary walls and/or mesangial areas and immunoglobulins deposits became more clear. These findings suggest as follows: (1) both IV col and 400-KD Lam, in particular 400-KD Lam, are possibly involved in the process of glomerulosclerosis: (2) both IV col and 200-KD Lam, in particular 200-KD Lam, are greatly involved in the process of new basement membrane-like materials formation in MN.