The adequacy of hepatic circulation in terms of oxygen supply-demand relation was assessed by measuring hepatic venous oxygen saturation (Shvo2) in patients. Among those with congenital cardiac lesions (n = 11), Shvo2 during the early postoperative period was markedly low as less than 20% in Fontan operation group (n = 5) with subsequent clinical findings of acute hepatic dysfunction. Significant correlations were found between Shvo2 values early after surgery and subsequent peak values in serum hepatic enzymes. Serum total bilirubin and prothrombin time started to deteriorate when Shvo2 became below 30%. Cardiac index, hepatic perfusion pressure and mixed venous oxygen saturation showed positive linear correlations with Shvo2, and central venous pressure (CVP) with an inverse relation. In chronic valvular disease (n = 28), those with NYHA class IV patients showed lower Shvo2 (average; 47.4%) at cardiac catheterization than the others (class-I; 66.4%, class-II; 63.9%, p less than 0.05). These results indicate that Shvo2 monitoring appears to be useful to assess the hepatic perfusion in terms of oxygen supply-demand relation in acute and chronic heart failure, and Shvo2 of 30% seems to be a critical level.