Primary sclerosing cholangitis is very rare in Japan. The aim of the present study was to identify the characteristics of such patients in Japan. A questionnaire was sent to the members of the Japanese Society of Gastroenterology and responses for 192 cases were analyzed. There was male predominancy (61%), and two peaks in the age distribution at diagnosis (20-30 years and 50-70 years). Bile duct damage was mainly intra + extrahepatic (69%) versus intrahepatic (17%) or extrahepatic (14%). The incidences of eosinophilia and positivity for anti-nuclear antibody were 27% and 30%, respectively. The incidence of associated inflammatory bowel disease was 21% (38 ulcerative colitis and 2 Crohn's disease). Chronic pancreatitis, gallstones, and biliary cancers occurred in 15%, 12%, and 4%, respectively, of the 192 patients. Patients less than 40 years of age had a higher incidence than the patients 40 years old or more of damage intra + extrahepatic bile ducts (89% vs 56%) and of associated ulcerative colitis (36% vs 9%), whereas the incidence of chronic pancreatitis was lower in patients aged less than 40 years (4%). The characteristics of patients with primary sclerosing cholangitis in Japan differ from those in other countries in regard to age distribution and the incidence of complications, and at least two different groups of patients seem to exist in terms of the degree of bile duct damage and the incidence of complications.