THE UNEXPECTED finding of an aneurysm of the carotid artery during the biopsy of a mass in the neck for histologic diagnosis can be catastrophic. In this regard, a false (traumatic) aneurysm of the common carotid artery in a 37-year-old man is reported. A review of the literature and suggestions for management are presented. The first ligation of a common carotid artery aneurysm was reported in 1805 by Sir Astley Cooper.1 Makins2 reviewed the British experience in the First World War of 86 cases of traumatic carotid aneurysms and found an overall mortality of 30%. Elkins and Shumacker3 reported only five cases of cervical traumatic aneurysms in a review of 883 arterial injuries in the Second World War. In another World War II series of 364 cases of vascular trauma, Shumacker4 reported four traumatic aneurysms. Two of those were "spontaneous cures" due to thrombosis of