1. Four cases of vascular injury during lumbar disc removal are reported, and the literature is reviewed. One of the cases is unique in that the inferior mesenteric artery was transected.

2. Clinical syndromes associated with various vascular injuries are discussed.

3. The possibility ofvascular injury should always be kept in mind during lumbar lam inectomy for disc prolapse. Unexplained hypotension is strongly suggestive of a vascular catastrophe. The advent of high output cardiac failure in the patient who has recently undergone lumbar disc removal is almost diagnostic of traumatic arteriovenous fistula.