200 Egyptian boys and men with urinary schistosomiasis were studied by clinical evaluation, radiography, quantitative egg excretion, bacterial cultures, and tests of renal function. Results were analysed by age, by symptoms (clinical grade), by presence of polypoid vs calcified schistosomal lesions (radiological stage), by presence or absence of obstructive uropathy, and by response to antischistosomal treatment. Age—Increasing age correlated slightly with decreasing egg excretion. Obstructive uropathy, bladder calcification, ureterolithiasis, and bladder retention increased linearly with age; polypoid lesions decreased linearly with age. Clinical grade—Age increased with increasing symptoms. Symptomatic patients excreted more eggs than those without symptoms. Non-functioning kidney was associated only with moderate or severe symptoms; other variables did not correlate with the grades. Radiological stage—Age increased from stage 1 (polypoid lesions only) to stage 2 (polypoid and calcified lesions) to stage 3 (calcified lesions only), as egg excretion decreased. Other variables were not different among the stages. Obstructive uropathy—Patients with obstruction were older than those without, and had higher frequencies of ureteral stenosis, ureterolithiasis, and bladder retention. Maximal urine concentration and phenolsulphonphthalein excretion were decreased in patients with obstruction. Treatment—Patients with improved urograms (including obstructive uropathy) following treatment were younger, excreted more eggs, and more frequently were in radiological stages 1 and 2 than patients without improvement. Improvement did not correlate with specific antischistosomal drugs or with the final percent reduction of egg excretion. These results suggest that the course of urinary schistosomiasis may be from polypoid to calcified lesions (radiological stage 1 to 3), associated with increasing age and decreasing egg excretion. However, clinical grade, bacterial urinary-tract infection, obstructive uropathy, and abnormalities of renal function are not stage-dependent. Although older age is associated with greater severity of symptoms and increasingly frequent radiographic abnormalities, appreciable morbidity occurs at all ages and in all stages of the disease in Egyptians in hospital. Prediction of reversibility of schistosomal uropathy can be made on the basis of age, egg excretion, and radiological stage.