Sixteen cases of unilateral and 5 cases of bilateral traumatic renal artery occlusion caused by avulsion or thrombosis are presented. The injury typically follows automobile-pedestrian accidents to young male subjects. Associated extrarenal injuries are usual but non-pedicle renal injury is infrequent. Suspicion of the unilateral injury depends upon recognition of absence of visible excretion at urography. The clue to bilateral occlusion is anuria. Diagnosis is confirmed by urgent arteriography. Hematuria was absent in 24 per cent and the injury was missed at laparotomy in 29 per cent of the initial explorations. Renal function was salvaged by arterial reconstruction in 2 cases, 12 hours and 5 months after injury respectively. Hypertension developed in 50 per cent of the cases and was generally mild.