Despite the wide use of the international classification of megaureters, there is a lack of clear concepts especially for congenital malformations. We performed a follow-up study in 132 children with 171 megaureters operated on during the past 13 years. In 24 additional cases reconstructive surgery was not feasible due to advanced damaging of the parenchyma. In 97% of 171 megaureters, resection of the distal stenosis and ureterocystoneostomy was successful. In 20%, additional ureteric tailoring was necessary. Only one patient had recurrent reflux, and reoperation for recurrent stenosis was indicated in less than 2.5%. Urographic studies revealed that postoperatively 38% of calices resumed a normal appearance, whereas 80% of the ureters were of normal caliber and had normal peristaltic activity. From this study it is concluded that ureteric stenosis should be treated operatively in refluxing and obstructive cases. As a rule, correction of bladder or urethral pathology does not obviate the need for ureter surgery.