ABSTRACT— The clinical, morphological and evolutive features of 60 patients with chronic hepatitis, presumably caused by non-A, non-B virus infection, have been retrospectively analyzed. In all the cases the disease began as an acute episode of viral hepatitis that was followed by persistently abnormal liver function tests. No patient had evidence of current or past hepatitis B virus infection and other known causes of chronic liver disease were excluded. Thirty patients had received blood transfusions in the recent past, five were drug addicts and the source of the infection was not identified in the remaining 25, in whom the disease was considered to be sporadic. Clinical or biochemical differences between patients with post-transfusional and sporadic non-A, non-B chronic hepatitis were not observed, but liver histology showed a higher proportion of patients with chronic persistent hepatitis in the sporadic (72%) than in the transfusional group (53%). On follow-up, sustained normalization of liver function tests was observed in 46% of the cases with sporadic hepatitis but only in 13% of the cases with post-transfusion hepatitis. These observations suggest that non-A, non-B chronic hepatitis is more severe in patients with transfusion-related infection than in sporadic cases.