Primary sclerosing cholangitis (PSC) leads to a progressive destruction of the intra- and extrahepatic bile ducts. The cause is unknown but genetic and immunological mechanisms may play a role. The median survival time from diagnosis to death is about 12 years. MRCP is almost equal to ERCP for diagnosing PSC and shows the typical localised or multifocal strictures and interfering segments of ectatic bile ducts. Liver histology can be helpful in making the diagnosis but is often unspecific and there is a large sampling variability. The treatment of PSC is disappointing. The combination of ursodeoxycholic acid with endoscopic dilatation is probably the best treatment. Patients with cirrhosis and/or recurrent cholangitis should be evaluated for liver transplantation as the outcome after liver transplantation is good, especially if there is no cholangio-carcinoma present and if the Child-Pugh score is not too high. There is also a need to treat the complication of PSC such as osteoporosis, cholangitis and the development of cholangiocarcinoma.