A retrospective study was performed to identify risk factors affecting the fate of liver allografts transplanted across the ABO barrier. Over a 5-year period, 30 patients received 31 emergency OLTs with ABOincompatible allografts. One-year graft and patient survival rates were 37.1% and 48.4%, respectively. This group was compared with 199 ABO-compatible OLTs performed under similar emergency conditions. Significantly higher incidence of rejection, hepatic artery thrombosis, and biliary stricture were found in ABOincompatible grafts. The graft or patient survival of patients with O blood group or fulminant hepatic failure was not affected by ABO incompatibility. In contrast, the 1-year survival of recipients with non-O blood group was only 13.3% and the 1-year survival of those undergoing retransplantation was only 27.7% after ABO-incompatible OLT. A multivariate analysis using the Cox proportional hazard model identified non-O blood group (relative risk 3.43) and retransplantation (relative risk 2.46) as the most important risk factors for patient survival after ABO-incompatible OLT. We conclude that the use of ABO-incompatible grafts is justified in emergency cases when no other donor is available, but should be proscribed in patients with non-O blood group. The value of ABOincompatible grafts in retransplantation is questionable and requires further investigation.