Activation of fibrinolysis remains a clinical problem in orthotopic liver transplantation. We have measured tissue plasminogen activator (t-PA), plasmin and α-2-anti-plasmin (α2AP) activities in plasma from 10 patients undergoing elective transplantation. t-PA activity increased during the anhepatic phase and immediately after graft reperfusion (p>0.001). This inrease could not be attributed to t-PA released by the donor liver. Overall transfusion requirements did not relate with either t-PA or α2AP activities individually, but were strongly correlated with the ratio t-PA/ α2AP (p>0.02). These results suggest that routine prophylactic use of antifibrinolytic agents may be beneficial.