The different forms of ureteral ectopy can be explained embryologically. Ureteral ectopy is caused by the premature appearance of the ureteral bud on the Wolffian duct. We find this rare malformation more frequent in women. We have seen 19 patients with ureteral ectopy, 15 with duplicated ureters and 4 patients with single ectopy. The symptoms are variable and not typical. The diagnostic procedures are discussed in detail. Ultrasonography and antegrade pyelography have been approved in diagnosis of ureteral ectopy. The operative treatment is rarely reconstructive, but mostly ablative.