Selected parameters of blood coagulation and fibrinolysis were determined in 25 men with severe alcoholic liver disease, in 10 men with mild disease, and in 10 patients with coincidental disease or liver disease not etiologically related to consumption of alcohol. Large variations in individual data, including unusually low and high values, were observed in several parameters. Usually, coagulation was prolonged in severe liver cirrhosis and frequently in mild cirrhosis. Plasminogen was decreased in severe, but not in mild disease. Euglobulin fibrinolytic activity, determined on bovine, plasminogen-rich fibrin plates, was decreased in severe as well as in mild disease. In 12 patients with severe disease, screened for inhibitors, slightly decreased inhibition of urokinase, tissue activator, and plasmin was observed. A carbontetrachloride poisoned patient showed defective coagulation and low plasminogen concentration, though fibrinogen was elevated; his euglobulin fibrinolytic activity was normal, but inhibition of tissue activator-induced fibrinolysis was markedly increased. Four hepatoma patients showed a marked increase in inhibition of tissue activator-induced fibrinolysis. The wide variety of changes indicates that the role of the liver in haemostatic homeostasis is a complex one. Our data suggest a correlation between inhibition of plasminogen activation and development of thromboembolic disease.