Abdominal ultrasonographic examination was performed in 61 hospitalized patients with chronic liver diseases and 253 school children from a village endemic for Schistosoma haematobium and were compared with 142 urban children without exposure to Schistosoma. The prevalence of ultrasound-detectable hepatomegaly and splenomegaly and the degree of periportal fibrosis was compared between those with and without S. haematobium infection. Among 13 patients with biopsy-proven schistosomal hepatic fibrosis, three with coarse changes secondary to S. mansoni infection showed grade III periportal fibrosis, while 10 patients with fine schistosomal hepatic fibrosis due to S. haematobium had borderline (two) or grade I (eight) changes. Ultrasound evidence of periportal fibrosis was not detected in patients with hepatic cirrhosis, chronic active hepatitis, or fatty infiltration. However, three of 14 patients with chronic persistent hepatitis had grade I periportal fibrosis and two had borderline changes. The frequency of ultrasound-detected hepatomegaly and splenomegaly was greater among rural S. haematobium-infected children (35.2% and 22.4%, respectively) than among noninfected rural (21.1% and 13.3%) and urban (16.9% and 4.9%) children. Also, the frequency of grade I periportal fibrosis was significantly greater (P less than 0.01) in S. haematobium-infected children (22.4%) than in noninfected rural (11.7%) and urban (0.7%) children. No patients with S. haematobium infections, either in the hospital or the village, had grade II or III periportal fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)