Ursodeoxycholic acid (UDCA) has beneficial effects in cholestatic diseases such as primary biliary cirrhosis, primary sclerosing cholangitis and cholestasis of pregnancy. In chronic hepatitis and alcoholic hepatitis, an effect of UDCA is uncertain. After organ transplantation (liver, bone, heart), favorable effects of UDCA which await confirmation were observed. UDCA very likely has a beneficial effect in children with Byler's and Alagille's syndrome, extrahepatic biliary atresia after the Kasai procedure and in cholestasis of cystic fibrosis. Unclear is the effect of UDCA in benign intermittent cholestasis (Summerskill-Tygstrup syndrome). Children with cholestasis and inborn errors of bile acid synthesis need additional administration of a primary bile acid (cholic acid, chenodeoxycholic acid). UDCA treatment in general does not lead to definitive cure of the disease but to improvement of laboratory parameters and possibly of symptoms and liver histology, and liver transplantation may be postponed to a later time point.