Professor Eberhard F. Mammen greatly contributed to the understanding of the relationship between hemostatic abnormalities and liver diseases. The physiology of the hemostatic system is closely linked to liver function because the liver parenchymal cells produce most of the factors of the clotting and fibrinolytic systems. Acute or chronic hepatocellular diseases and hepatic failure including liver cirrhosis, vitamin K deficiency, liver surgery including liver transplantation, and sclerotherapy of bleeding esophageal varices, which were classified by Prof. Mammen, show various hemostatic abnormalities in the coagulation system, fibrinolytic system, platelets, and the reticuloendothelial system. Hemostatic abnormalities in patients with hepatic failure or in those that have undergone liver surgery are similar to those in disseminated intravascular coagulation. Prof. Mammen also contributed to the study of vitamin K-dependent clotting factors, antithrombin, and hemostatic molecular markers. Partly based on this work, the prothrombin time-international normalized ratio, several hemostatic molecular markers, and antithrombin therapy have been recently developed for the diagnosis and treatment of thrombosis.