This is the first report of glomerular disease in a 13-year-old boy who was a carrier of hepatitis B virus both mesangial IgA and subepithelial IgG deposits in the glomeruli at the same time. The clinical findings resembled those of IgA nephropathy. On electron microscopy, electron-dense deposits were identified not only in the mesangium but also on the epithelial side of the glomerular basement membrane. Immunofluorescence and immunoperoxidase staining demonstrated hepatitis B surface antigen and hepatitis B core antigen in the glomeruli but hepatitis B e antigen was not detected. Our findings suggest hepatitis B virus antigens have a pathogenetic role in the simultaneous development of these two glomerulopathies.