In a follow-up study of 85 patients with chronic aggressive (active) hepatitis (CAH) repeated liver biopsies and/or autopsy liver sections were available in 74 cases. The median time of observation was 45 months. Cirrhosis was demonstrated in 38 patients, and cirrhosis was suspected in a further five cases. Fifteen patients showed convincing histological improvement; and the remaining 16 still had chronic hepatitis. Twenty-six patients died during the observation period, seven of these of liver failure after development of cirrhosis. The clinical follow-up of the 59 survivors (median observation time 69 months) showed biochemically active liver disease in 11 cases, all having cirrhosis or chronic aggressive hepatitis in the last biopsy. The clinical findings were correlated with the morphological follow-up diagnosis and the immunosuppressive treatment. Comparison of the initial histological, clinical, and serological variables was made in two well-defined follow-up groups. There were more females, and marked portal inflammation, abnormal bile duct epithelium, and circulating autoantibodies occurred more frequently in the group with later development of cirrhosis than among the patients with subsequent morphological improvement. The results thus suggest candidates for thorough follow-up and more intensive immunosupressive or other treatment.