Isolated injury to the renal pelvis following blunt abdominal trauma is very rare. However, a pre-existing renal abnormality will increase the risk of rupture. We present a 24-year-old man with rupture of the left renal pelvis following blunt abdominal trauma. He had pre-existing left ureteropelvic junction (UPJ) obstruction. Delayed computed tomography scan with excretory phase revealed contrast medium extravasation from the left UPJ, and left renal pelvis rupture was diagnosed. He was managed successfully with ureteral double-J stenting for 2 months.