Primary sclerosing cholangitis is a chronic disease of the intra- and extrahepatic bile ducts leading to obstructions and dilatations followed by liver cirrhosis and in some cases cholangiocarcinoma. In 50% of cases primary sclerosing cholangitis is associated with inflammatory bowel disease. The cause of the disease is unknown and many questions concerning the pathogenesis still remain open. In recent years our knowledge of the natural course, the risk of cholangiocarcinoma and the possibility of medical, endoscopic and surgical treatment has increased. Ursodeoxycholic acid, endoscopic treatment and liver transplantation have become standard therapeutic procedures. This book is the proceedings of the Falk Workshop held on October 3, 1997, in Freiburg, Germany (Part II of the Liver Week Freiburg 1997), and covers the most important aspects of this fascinating disease.