The activities of Hageman factor, high molecular weight kininogen (HMWK), and prekallikrein were studied in patients who had chronic active hepatitis and cirrhosis. Serum HMWK and prekallikrein activities were decreased in chronic active hepatitis and cirrhosis, but Hageman factor activity was low in cirrhosis only. The reduction of prekallikrein, HMWK, and Hageman factor was dependent on the degree of liver failure. Similar prekallikrein values were found in serum samples, activated or not, with an excess of Hageman factor and HMWK, which suggests that the decrease of prekallikrein in liver disease is not influenced by the simultaneous decrease of Hageman factor and HMWK.