Adoptive immunity transfer has been reported to be effective in clearing chronic hepatitis B virus (HBV) infection. Two hundred twenty-six patients who received allogeneic bone marrow transplantation (BMT) between May 1990 and September 1995 were screened for hepatitis B markers. Twenty-one patients were hepatitis B surface antigen (HBsAg) positive before BMT. The median follow-up period was 20 months (range, 2-59 months). Two of these patients had sustained clearance of HBV infection after transplantation. Both patients were hepatitis B e antigen (HBeAg)-negative, hepatitis B e antibody (anti-HBe)-positive, and serum HBV DNA-negative (by dot-blot hybridization) before BMT. Both had a flare in the serum alanine transaminase (ALT) level around the time of HBsAg clearance. Sustained clearance of HBsAg was observed in 2 of the 5 patients who received hepatitis B surface antibody (anti-HBs)-positive marrow but in none of the 16 patients who received anti-HBs-negative marrow (P < .05). One additional patient who received anti-HBs-positive marrow had transient HBsAg seroconversion. Among the 18 patients who remained persistently HBsAg-positive after BMT, 3 had HBeAg seroconversion and 3 had reversion to HBeAg positivity. In this study, we found a significant association between clearance of HBV infection and anti-HBs-positive bone marrow donors. Adoptive immunity transfer is effective in clearing HBV from patients with chronic HBV infection.