Chronic hepatitis is a conspicous and frequent finding in schistosomiasis. Microscopic characteristics of such hepatitis are presented, with especial emphasis on its signs of activity and the absence of correlation with schistosomal granulomas. It is suggested that the hepatitis results from, delayed type hypersensitivity reactions to schistosomal antigens and that it is an important pathosgenetic pathway to portal fibrosis, flebosclerosis, perineural fibrosis, neural hypertrophy and ductal and ductular proliferations, which are characteristic findings of advanced schistosomiasis.