Purpose:To clarify the diagnosis and management of ureteral obstruction owing to vena cava orcongenital crossing vessels. Methods: Preoperative sonography, intavenous urography (IVU), retrograde urogra-phy or magnetic resonance urography(MRU) were performed in 19 cases of patients for evaluation of hy-droureteronepherosis. Combined with magnetic resonance imaging(MRI) or cavography, retrocaval ureter couldbe detected. Colour Doppler imaging was used to detect crossing vessels. During operations, retrocaval (8cases) or retroiliac (1 cases) ureters were excised, crossing vessels (10 cases) were divided then ureteroureteralanastomosis or dismembered pyeloplasty (Anderson-Hynes) were completed. Results:3 to 6 months after opera-tions, hydroureteronepherosis was lightened to different extends in all patients. After median follow-up of 15.7months (range 1 to 4.5 years), hydroureteronepherosis was found in one patient. Conclusions:Disorder of bloodvessels should be considered in the differential diagnosis of extrinsic ureteral obstruction. Sonography, IVU,MRI combined with cavography, color Doppler imaging are of great value in the diagnosis of those conditions.Early diagnosis and treatment are very important.