The possibility of vascular injury should always be kept in mind during lumbar laminectomy. Patients with pre-existing vascular disease are predisposed to injury. Unexplained hypotension is highly suggestive of a vascular catastrophe and is an indication for more detailed examination, sometimes laparotomy. If the patient's clinical condition is stable, consider arteriography. The development of high-output cardiac failure in a patient who has recently undergone lumbar laminectomy is almost diagnostic of traumatic arteriovenous fistula. The best prognosis for recovery of acute vascular interruption occurs with immediate treatment within 24-48 hours. Continued awareness of the possible occurrence of these injuries and familiarity with their various manifestations will facilitate early diagnosis, prompt operative repair, and improved mortality.