The effects of cholic acid and eight related cholanic acid analogs on bile flow and biliary excretion of bile salts and cholesterol were studied in rabbits. Bile acids were infused intravenously in anesthetized rabbits. In all except hyodeoxycholic or lithocholic acid treated animals increases in bile flow were recorded within 10 minutes during infusion of bile acid-The increase in bile f1ow associated with an increase in bile salt level in bile after cholic acid infusion was observed, however, there were little changes in biliary, cholesterol levels. Bile salt level in bile was not associated with bile flow after chenodeoxycholic acid infusion but the cholesterol level in bile was significantly increased. Ursodeoxycholic acid similarly increased cholesterol but to a lesser extent. Keto-forms of chenodeoxycholic acid were without action. These results indicate that both cholic and chenodeoxycholic acids have the capacity to alter specific biliary excretion of bile components, the former on bile salts and the latter on cholesterol-a precursor of bile acids in bile.