The glomerular pathology and hepatitis B virus (HBV) antigens in renal biopsies were investigated in 100 consecutive patients with both primary glomerulonephritis and positive serology for hepatitis B surface antigen (HBsAg). Glomerular HBV antigens including HBsAg, hepatitis B core antigen (HBcAg), and hepatitis B e antigen (HBeAg) were examined in frozen tissue using both polyclonal and monoclonal antibodies. HBV serology and glomerular antigens were correlated. Using monoclonal antibodies, at least one of the three HBV antigens was detectable in glomeruli in 39% of the cases. These findings correspond mainly to detectable glomerular HBsAg and HBeAg in 22.3 and 28.4% of cases, respectively. A good correlation was found between glomerular and serum HBeAg but not observed for HBsAg. Serum HBcAg was not examined and not correlated with glomerular staining. When the diagnosis of HBV-related glomerulonephritis was based strictly on detectable glomerular antigens, three distinctive morphologies were identified: membranous nephropathy, mesangiocapillary glomerulonephritis, and mesangial proliferative glomerulonephritis with immunoglobulin A (IgA) deposits (IgA nephropathy). Each of these lesions may be seen in pure form or occasionally in overlapping form leading to double glomerulopathies. Glomerular HBeAg and HBsAg were associated with subepithelial and mesangial immune complexes, respectively. Rare overlap between membranous nephropathy and IgA nephropathy further emphasized the distinctive pathology of HBV-related glomerulonephritis and the independent etiological role of HBeAg and HBsAg. In other glomerulonephritis, which rarely demonstrated glomerular HBV antigens, the pathogenetic role of chronic HBV infection remains to be proven.