In order to compare clinical versus ultrasound based diagnosis of Schistosoma mansoni induced periportal fibrosis (pF) 536 infected Sudanese schoolchildren underwent clinical and sonographical examination. A liver exceeding 3 cm in sternal line and a palpable spleen were considered pathological. Ultrasound criteria for age dependent organometry of a Central European cohort were used as reference. Based on clinical criteria 190 children (35.4%) had hepatomegaly, whereas according to ultrasound results the rate was only 11.4%. Splenomegaly was detected in 77 cases (14.4%) by clinical means, but in 196 by ultrasound (36.6%). The sensitivity of clinical parameters as indication of pF was around 50%. Results for ultrasound detected organomegaly were only slightly better. It was concluded that assessment of liver and spleen sizes was of limited value as an indication for pF and that a considerable discrepancy existed between clinical and ultrasound based assessment of hepato- and splenomegaly.