Ultrasonographic evaluation of 213 patients with urinary schistosomiasis in different age groups was performed in an endemic area of the Democratic Republic of Congo. The results were compared with 94 age matched controls without urinary schistosomiasis. In patients the bladder showed thickening of the wall, polypoid lesions of the mucosa and bladder wall, calcifications and urinary retention. Urinary tract obstruction, predominantly unilateral, was demonstrated. The lesions increased in severity with the intensity of infection, parallel to an increase in ova excretion. Children aged between 8 and 19 years were most severely affected. Pathological lesions of the upper urinary tract were rare in patients over 25 years of age. The combination of morphological abnormalities was interpreted as being specific for urinary schistosomiasis as they did not occur in the control group. It is suggested that real time ultrasonography may be used to identify morphological lesions in urinary schistosomiasis.