We studied prevalence and incidence of autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis in a Norwegian population. A search in patient databases was performed and medical records from the period 1985-94 were reviewed. Commonly accepted diagnostic criteria were used for inclusion. All three diseases were found to be rare, with a marked female preponderance in primary biliary cirrhosis (female 21/male 0) and to a lesser extent in autoimmune hepatitis (female 20/male 9). The age distribution shows that autoimmune hepatitis and primary sclerosing cholangitis are diagnosed in patients who are on an average 12 years younger than patients with primary biliary cirrhosis. The mean annual incidence was 1.6/100,000 for autoimmune hepatitis, 1.2/100,000 for primary biliary cirrhosis and 0.7/100,000 for primary sclerosing cholangitis. The end of study point prevalence was 14/100,000, 12/100,000 and 5.6/100,000, respectively.