The purpose of this study is to clarify the clinical and pathological features of glomerulonephritis associated with hepatitis B virus infection (HBV-GN) in adults. Of the 47 adult cases with HBV-GN, 7 cases were diagnosed as minor glomerular abnormalities, 19 as mesangial proliferative GN (mild 13, moderate 4, severe 2), 11 as membranous GN, 10 as membranoproliferative GN (type I 2, type III 8). Indirect immunoperoxidase method using monoclonal antibody raised against HBV related antigens (HBsAg and HBeAg) revealed glomerular deposition of only HBsAg in 10 cases, only HBeAg in 2, and both antigens in 10. Deposition of HBeAg was observed dominantly along the capillary walls in comparison with that of HBsAg (p less than 0.01). Additionally, in 4 cases diagnosed as the IgA-GN because of the IgA dominant mesangial deposition and normal liver function, HBV related antigens were detected in the mesangial areas. Aggravation of renal function with respect to serum creatinine level, only 0.6-0.8 mg/dl increased, was demonstrated in 4 of 27 cases followed up for more than a year. These results suggest that the high incidence of membranous GN and membrano-proliferative GN was observed in HBV-GN in adults. HBsAg as well as HBeAg may contribute to the pathogenesis of this glomerulonephritis, and then HBsAg may play in capillary walls and mesangial areas, whereas HBeAg in capillary walls mainly. And the possibility exists that HBV related antigens are the responsible antigenic agents in some cases of IgA-GN.