Ninety-five urinary fistulas have been produced at various urinary tract levels in 62 infants and children, aged 20 days to 13 years, for uni- or bilateral megaureter and hydronephrosis 14 days to 16 months prior to major reconstructive-plastic surgery. Efficacy of draining (21 cystostomies, ureterostomies and nephropyelostomies) and nondraining (74 ureterocutaneostomies) techniques was evaluated 2-6 months or later using clinical, laboratory, X-ray, tracer and urologic cinematographic studies. Fistula application and removal maneuvers and complications are described. The draining techniques were found to be inefficient in prolonged preliminary urinary diversion and to be associated with frequent infection relapses and less satisfactory results of plastic surgery. Ureterocutaneostomy proved to be the most reliable and convenient method of prolonged drainage even though it required additional operations to replace the patent ureters. The drainage should be prolonged to 12-16 months if the urinary tract deteriorates, especially in young children.