In a 5-year period 48 (14%) of 336 patients with ulcerative colitis were found to have hepatobiliary disease. The bile ducts were examined in 35 of these patients, and optimal visualization of both intra- and extra-hepatic bile ducts was obtained in 26. Duct changes compatible with sclerosing cholangitis were found in 14 patients. This finding of sclerosing cholangitis in 4% of all patients admitted with ulcerative colitis by far exceeds previous estimations on the incidence of sclerosing cholangitis in ulcerative colitis. The entire colon was usually affected, and the symptoms of the bowel disease were most often mild or moderate. The age at the onset of the colitis was usually below 20 years in patients with combined ulcerative colitis and hepatobiliary disease. In most patients the hepatobiliary disease gave no symptoms. Biochemical data and the histological findings in the liver biopsies did not distinguish between patients with hepatobiliary disease with and without sclerosing cholangitis. Our follow-up study has so far shown that most patients with sclerosing cholangitis remain asymptomatic for a considerable period of time.