A chart review of chronic hepatitis cases at the Department of Infectious Diseases, Roslagstull Hospital, Karolinska Institute, Stockholm, Sweden, revealed 37 patients with chronic non-A, non-B hepatitis, caused by blood transfusions or intravenous gammaglobulin infusions. They had been followed up long-term, mean 46 months (range 10-149). During the initial hepatitis episode most patients had been anicteric and 13/37 (35%) asymptomatic. Yet, the majority developed progressive liver disease with chronic active hepatitis, with or without histological signs of cirrhosis. Thus, 10/18 (56%) on whom a liver biopsy had been performed within 7-12 months had chronic active hepatitis, four (22%) with histological signs of cirrhosis, and of the five patients biopsied after greater than or equal to 5 years of follow-up, three (60%) had histological signs of cirrhosis. Accordingly, as the duration of follow-up increases, an increasing number of patients with post-transfusion non-A, non-B hepatitis seem to develop cirrhosis.