Cholestasis syndromes are characterized by a reflux of compounds usually excreted with bile. ATP dependent carriers and cytoskeleton proteins guarantee physiological bile flux. There are several clinical conditions in which this system is affected. Intrahepatic cholestasis is characterized by damage to hepatocytes or intrahepatic bile ducts. Primary biliary cirrhosis and primary sclerosing cholangitis represent examples of cholestatic chronic liver disease. The pathogenesis of these two conditions seems to be mediated by immunological reactions. Moreover, hepatitis viruses are able to induce cholestasis.