Mitochondrial fractions were obtained from purely isolated hepatocytes of the normal and cirrhotic livers. Mitochondrial function of isolated hepatocytes was evaluated to compare between those from the normal and those from the cirrhotic livers in addition to the evaluation of the mitochondrial function of the normal and cirrhotic liver tissues. Respiratory control, ADP/O ratio and ATP synthesis were significantly lower in the cirrhotic liver tissue than those in the normal liver tissue. However, the mitochondrial function of isolated hepatocytes showed no difference between normal and cirrhotic groups. By electron microscopic examination, debris was more observed in the mitochondrial fractions from the normal and cirrhotic tissues compared to those from hepatocytes. However, no difference of the shape and size of the mitochondria was seen between the fraction from hepatocytes and that from the tissue in each group. These results suggest that as far as hepatocyte itself is concerned, the cirrhotic liver preserves the sufficient function as well as the normal liver.