The urinary and fecal bile acids of thirteen male patients with liver cirrhosis were analyzed by gas chromatography and gas chromatography-mass spectrometry to obtain information on their keto bile acid excretion. 3 alpha-Hydroxy-12-keto-5 beta-cholanoic, 3 alpha,12 alpha-dihydroxy-7-keto-5 beta-cholanoic, 3 alpha,7 alpha-dihydroxy-12-keto-5 beta-cholanoic and 3 alpha-hydroxy-7,12-diketo-5 beta-cholanoic acids were found in the urine of ten patients. In four of these patients, keto bile acids were the main bile acids excreted in the urine. However, the ratios of fecal keto bile acids to the total fecal bile acids in these four patients were similar to those in the other six patients whose urinary excretion of keto bile acids was low. Three of the four patients had clinical abnormalities, such as ascites, esophageal varices or a history of hepatic encephalopathy, that may indicate advanced liver dysfunction and/or presence of collateral circulation. These findings suggest that the occurrence of keto bile acids in the urine might be ascribed to the escape of these acids from reduction to hydroxy-forms in the liver, not to bacterial over-production in the intestine. However, the mechanism and significance of the presence of keto bile acids in the urine are still unknown.