A study of double immunofluorescence staining of immunoglobulins and sialic acids in the glomeruli from patients with membranous nephropathy was described. Renal biopsy specimens from patients with membranous nephropathy were stained with rhodamine-labeled limulus polyphemus (LPA) and tricum vulgaris (WGA). The binding of LPA or WGA was hardly observed in the glomerular capillary walls from patients with membranous nephropathy although the deposition of immunoglobulin was marked. Both binding of LPA and deposition of IgG in the glomerular capillary walls were observed in only one out of nine patients with membranous nephropathy (11%). In that case, binding of LPA was observed in the inside of glomerular capillary walls although the deposition of IgG was observed on the outside of the walls. It was suggested that decrease of sialic acids in the glomerular capillary walls might be due to deposition of IgG in some patients with membranous nephropathy.