We performed a retrospective survey in 62 hematopoietic cell transplantation (HCT) centers in Japan in which all HCTs performed between 1986 and 1998 were reviewed, and those involving hepatitis B virus surface antigen (HBsAg)-positive donors were identified. One hundred and thirty-five patients who underwent allogeneic HCT (alloHCT) were studied for complications related to hepatitis B virus (HBV) or hepatitis C virus (HCV). The median follow-up period was 24 months. Positivity for HBsAg was observed in 32 patients (24%) throughout the study. Twenty-six of the 32 patients were HBsAg carriers before alloHCT, whereas the remaining 6 became HBsAg(+) after alloHCT. Forty-two recipients were anti-HBs antibody (HBsAb)-positive, and 58 recipients (43%) were HCV Ab(+). Eleven of 26 (42%) HBsAg(+) recipients survived between >4 and >119 months. Six of 26 cases received transplants from HBsAg(+) donors, and, although they had not developed acute graft-versus-host disease, 4 of 6 died of hepatic and renal failure within 10 months after HCT. After transplantation, 5 patients showed serologic evidence of HBV reactivation, whereas 4 patients showed evidence of an immune response to HBV. Viral reactivation occurred during the tapering of the immunosuppressive agent. However, 3 of 5 were alive at the time of this report, suggesting that reactivation is not directly correlated with severe liver dysfunction. Seventeen patients (13%) of 135 recipients developed hepatic failure. Eight (47%) of 17 were diagnosed with fulminant hepatitis and 5 (29%) with veno-occlusive disease (VOD). VOD was observed in 12% of both HBsAg(+) and HCVAb(+) patients. In this study, the relatively high incidence of HBV events occurred after alloHCT, and, therefore, we should consider a protocol for active immunization of donors and recipients against HBV. Moreover, although the presence of HBV or HCV is not a contraindication for alloHCT, we recommend a careful follow-up of recipients after transplantation, especially during immunosuppression tapering.