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 Makins 2 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 Shumacker 3 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, Shumacker 4 reported four traumatic aneurysms. Two of those were "spontaneous cures" due to thrombosis of