Ursodeoxycholic acid is used to reduce the cholesterol saturation of bile and to promote the dissolution of gallstones. The cholesterol saturation of bile is reduced by Ursodeoxycholic acid, allowing gradual solubilization of cholesterol gallstones. Cholesterol of secretion into bile is reduced and bile acid secretion rate is increased during Ursodeoxycholic acid treatment without a reduction in phospholipids.