BACKGROUND Bleeding complications frequently occur during orthotopic liver transplantation (OLT), particularly in patients with liver cirrhosis. Enhanced fibrinolytic activity in plasma was seen to play a key role in the development of the hemostatic disorder and of hemorrhages. Aprotinin, a serine protease inhibitor, has been used in the prevention and/or treatment of hyperfibrinolytic states. METHODS In the present study, the effect of aprotinin on bleeding complications and transfusion requirements was investigated in OLT patients with liver cirrhosis. Seven consecutive cirrhotic patients undergoing OLT were infused with aprotinin following an original protocol (1,000,000-KIU intravenous loading dose plus 500,000 kallikrein-inhibitory units per hour until skin closure). Seven previous cirrhotic OLT patients not receiving aprotinin were used as controls. RESULTS In the treated group, a significant decrease in the number of transfused units of packed red cells (48.7%, p < 0.01), fresh-frozen plasma (24.4%, p < 0.05), platelets (35.9%, p < 0.01), and autologous blood (55.2%, p < 0.01) was observed as compared with the control group. Moreover, the mean length of operation was significantly shorter in the aprotinin-infused patients than in untreated patients (8.3 +/- 1.2 vs. 10.1 +/- 1.8 hours, respectively; p < 0.01)). In the aprotinin-treated group, the antifibrinolytic efficacy was confirmed by the lack of increase in D-dimer levels and decrease of fibrinogen in plasma; on the contrary, these changes were always seen in the group not receiving aprotinin. CONCLUSIONS Infusion of aprotinin during OLT in cirrhotic patients can be recommended for the prevention of hyperfibrinolysis-triggered bleeding, thus reducing transfusion requirements. A possible protective effect on the primary nonfunction of the grafted liver is suggested.