Retroaortic left renal vein joining the left common iliac vein is a rare congenital anomaly in the development of the inferior vena cava. To our knowledge, only one case has been reported in the literature; however, its imaging features have never been described. A 27-year-old male presented with a 1-year history of recurrent right flank pain, dysuria, hematuria, and fever (39 degrees C). Computed tomography and MR venography showed a retroaortic left renal vein joining the left common iliac vein. We present the CT and MR venography findings and discuss their feasibility in showing this congenital anomaly.