Disruption of the ureter is very rarely caused by a blunt trauma, only 12 cases having been reported in Japan. A 20-year-old male suffered from a blunt abdominal trauma in a traffic accident. Although his urinalysis showed no abnormalities, a dull pain in the left flank region persisted for over a week after the injury. Under the suspicion of renal or ureteral injury, an excretory urogram (DIP) was conducted. The form of renal pelvis and calyces was almost normal on both sides, while extravasation of contrast medium was recognized around the lower pole of the left kidney. The retrograde pyelogram of the left side revealed that catheterization was possible up to 30 cm from the ureteral orifice, but the injected medium leaked into the retroperitoneal space making it impossible to visualize the left renal pelvis and calyces. An operation was performed under the diagnosis of left ureteral injury on the 19th day after trauma. The left ureter was completely disrupted 2 cm distally from the ureteropelvic junction. An end to end anastomosis of the ureter was done with 6-0 Dexon sutures. The DIP taken on the 25th day after the operation showed slight dilatation of the left pelvis and calyces. However, the renogram conducted 6 months after the operation demonstrated a normal pattern on both sides.