Goals: A retrospective study of pretransplantation risk factors predisposing to liver injury following bone marrow transplantation (BMT). Background: Liver complications are a major cause of morbidity and mortality following BMT. Determination of the pretransplantation factors that are likely to lead to liver injury may allow earlier diagnosis after BMT and may possibly improve prognosis. Study: Medical records of BMT patients were reviewed, and results of serial liver function tests and HBV/HCV serology during the pre- and posttransplantation 1-year period were noted. Presence of liver injury was defined as alanine aminotransferase levels twice the upper limit of normal. Forty-four allogeneic and 17 autologous BMTs, performed between 1990 and 2000, were analyzed in the study. Results and Conclusion: One-year survival was 77% (34 of 44 patients) for allogeneic BMT and 52% (9 of 17 patients) for autologous BMT. Seventy-two percent (32 of 44) of allogeneic transplant recipients and 47% (8 of 17) of autologous transplant recipients had liver injury during the first year of BMT. The most frequent causes of liver injury were graft-versus-host disease and drug hepatotoxicity for allogeneic BMT and drug hepatotoxicity for autologous BMT. Fulminant hepatic failure occurred in one allogeneic transplant recipient who was a pretransplantation HBV carrier and led to death. Multivariate regression analysis showed that pretransplantation HBV/HCV positivity and pretransplantation elevated liver enzyme levels of any cause were predictive risk factors for post-BMT liver injury, and close follow-up, early diagnosis, and treatment are highly recommended for BMT patients with these risk factors.