In a study of 234 liver transplants the 2-year graft survival for ABO-compatible elective (80%) or emergency (76%) liver transplants was significantly higher than that for ABO-incompatible emergency liver transplants (30%). The low survival of ABO-incompatible liver allografts was therefore not related to the emergency conditions. Among 17 patients who received ABO-incompatible liver allografts, primary humoral rejection, with haemorrhagic infiltration of portal tracts and deposition of IgM and fibrinogen on sinusoidal and endothelial cells, developed in 6. Other disadvantages of ABO-incompatible liver allografts were significantly higher frequencies of severe rejection crises, arterial thrombosis, and cholangitis. However, the 1-year survival rate of the patients who received ABO-incompatible grafts was 66%, so the use of ABO-incompatible liver grafts is justifiable in emergencies, when no other donor is available; such transplants may help to save the patient, even at the cost of retransplantation in half of the cases.