To evaluate the therapeutic effect of recombinant human alpha-interferon (alpha-IFN) on hepatitis B virus associated glomerulonephritis (HBV-GN) and the relationship between the seroconversion of viral antigens and the change of proteinuria, the hepatitis B viral markers and urinary protein were monitored during alpha-IFN treatment in 8 male adult patients who (1) were positive in serum HBsAg and HBeAg, (2) had chronic hepatitis, (3) had persistent proteinuria > 1 g/day, and (4) showed glomerulonephritis on kidney biopsy. alpha-IFN was given at a dose of 3 million units, subcutaneously, three times a week for 6 months. Kidney biopsy specimens showed membranoproliferative glomerulonephritis (MPGN) in 4 patients, mesangial proliferative glomerulonephritis (MesPGN) in 2, and membranous glomerulonephritis (MGN) in 2 patients. Seven of the 8 patients received a 6-month course of alpha-IFN therapy; 1 patient with MGN quitted therapy 2 months after the initial dose because of side effects. In 5 of the 7 patients who received a 6-month therapy, serum HBeAg disappeared, and anti-HBe appeared during the therapy. In 2 of these 5 patients, HBeAg reappeared, in 1 during alpha-IFN therapy and in 1 9 months after the last dose of alpha-IFN. The hepatitis B viral markers of the patient who received a 2-month therapy did not change. HBs antigenemia persisted in all patients. In all 4 patients with MPGN, serum HBeAg was transiently or persistently converted to negative, but the proteinuria persisted. Both patients with MesPGN showed remission of proteinuria; however, only 1 patient had seroconversion of HBeAg. In 2 patients with MGN, proteinuria persisted. In conclusion, alpha-IFN at the doses given was not effective in MPGN type of HBV-GN. Improvement of proteinuria was achieved in MesPGN patients without disappearance of HBs antigenemia which is the finding against the possible role of HBsAg in the pathogenesis of this type of HBV-GN.