About one-half of patients with ulcerative colitis develop abnormal liver function tests at some time during the course of the illness. This should prompt an investigation for primary sclerosing cholangitis and other common hepatobiliary diseases. Primary sclerosing cholangitis occurs in 2-10% of patients with ulcerative colitis. The diagnosis of primary sclerosing cholangitis is most often made by endoscopic retrograde cholangiography. Liver histopathology is often inconclusive but magnetic resonance cholangiography shows promise as a useful non-invasive diagnostic tool. Cholangiocarcinoma complicates 20-40% of patients with end-stage primary sclerosing cholangitis and is now one of the most common causes of death in patients with ulcerative colitis. Distinction between benign and malignant strictures can be difficult and is best done with a combination of clinical suspicion, repeated imaging for mass lesions, cholangiography, and endoscopic brushings and/or biopsies. Dominant lesions of the common bile duct or common hepatic duct produce progressive jaundice and liver damage. Early treatment may improve prognosis. Single strictures can be dilated endoscopically. If the stricture is more complicated and extends into the intrahepatic ducts or there is suspicion of cholangiocarcinoma, surgical resection may be more appropriate. Liver transplantation should be considered in end-stage disease.