Morbidity in schistosomiasis is caused by a granulomatous response to Schistosoma mansoni eggs deposited in peripheral portal veins. Ultrasonography has been useful to assess the impact of control programs on the prevalence of hepatic fibrosis. In the present study, ultrasonographic criteria proposed by the World Health Organization were used to classify the degree of hepatic fibrosis in 164 schistosomiasis patients from an endemic area of Brazil. The majority of subjects (89%) had degree I or II hepatic fibrosis. Periportal tract thickness, portal vein diameter, splenic vein diameter, and spleen size were positively correlated (P < 0.01). Ultrasonography was repeated on 21 patients one year later and hepatic fibrosis had progressed in 17. Ultrasonography was performed after treatment on 39 subjects and periportal fibrosis had regressed in 27.