We examined the oxygen content in the hepatic arterial, hepatic venous and portal venous blood to evaluate the oxygen supply to the liver and hepatic oxygen extraction in cirrhosis. The arterial-portal venous difference of the oxygen content was within the normal range in cirrhosis patients, although the oxygen content of the hepatic artery and portal vein was lower than in the control patients. The hepatic venous oxygen content was normal in the cirrhosis patients. The oxygen tension and saturation were always higher in the splenic vein than in the other branches of the portal system. Oxygen was supplied chiefly by the hepatic artery, and arterial oxygen extraction was normal in cirrhosis. In addition, there was no change in arterial extraction during oxygen inhalation by cirrhosis patients. Portal venous oxygen extraction was decreased in cirrhosis and was increased by oxygen inhalation. These findings indicate the autoregulation of hepatic oxygen through a mutual relationship between the hepatic arterial and the portovenous oxygen supply.