An 81-year-old man underwent an aortobifemoral bypass graft because of a ruptured abdominal aortic aneurysm. His postoperative recovery was complicated by unilateral lower limb paralysis caused by perioperative ischemia of the lumbosacral plexus. Ischemic lumbosacral plexopathy is an uncommon complication after infrarenal aortic surgery with serious morbidity. Despite a good surgical technique and knowledge of the vascularization of the spinal cord, its occurrence remains unpredictable.