Chronic hepatitis was diagnosed on the basis of biochemical, immunological and morphological criteria in 153 cases. On the evidence of observations for a mean period of four years the prognosis of chronic persistent hepatitis is regarded as favourable, no progression to chronic aggressive hepatitis or to cirrhosis having been observed in any of the cases. On the other hand, chronic aggressive hepatitis was found to progress to cirrhosis in 12 out of 65 cases. Cirrhotic transformation was more frequent in hyperactive processes (8 out of 25 cases). The sera of patients with primary hepatocellular carcinoma showed low immunoglobulin concentrations, with increased coeruloplasmin and reduced transferrin levels.