Ursocholic acid (UCA) is the 7 beta epimer of the naturally occurring primary bile acid, cholic acid. Cholic acid (CA) administration does not reduce biliary cholesterol saturation unless its 7 alpha dehydroxylation to deoxycholic acid (DCA) is prevented by concomitant antibiotic treatment. It was shown, that UCA caused diarrhoea and hypercholesterolemia, had only a modest effect on biliary cholesterol saturation and thus UCA was not able to replace ursodeoxycholic and chenodeoxycholic acid for medical treatment of gallstones. In addition, as discovered, during ursocholic acid therapy the synthesis of primary bile acids continued whereas the formation of secondary bile acids was greatly increase.