Of 164 children presenting with gross or microscopic hematuria during a 5-year period 111 (68 per cent) were proved by clinical features or renal biopsy to have glomerulonephritis. Extraglomerular origin of hematuria was documented in only 25 (15 per cent). No definite diagnosis could be made in the remaining 28 (17 per cent) with isolated hematuria but the clinical picture was similar to that of the patients with mild glomerular lesions. Followup in 59 of 68 children confirms previous reports that isolated hematuria in childhood is usually a benign condition. Although excretory urography, urine cultures and serum complement measurements should be done to eliminate uncommon causes of hematuria, invasive studies, such as renal biopsy and cystoscopy, are not indicated routinely.