The laboratory counterpart of tubular antigen-mediated membranous glomerulonephritis in humans was produced in rats by a single injection of homologous nephritogenic tubular antigen with adjuvant. The rat developed membranous glomerulonephritis with typical clinicopathologic features of human nephritis mediated by the tubular antigen, i.e., massive proteinuria and diffuse thickening of glomerular basement membranes due to deposition of tubular antigen-antibody complexes which were demonstrated by immunofluorescent technique. The nephritogenic tubular antigen was solubilized by pronase digestion, further purified by gel filtration, and demonstrated to have the same physicochemical properties as the human tubular antigen which was found in the deposits together with beta1C- and immunoglobulins in the glomeruli of patients with membranous glomerulonephritis.