The authors report 9 cases of carotid artery aneurysms in 7 patients from a total of 564 carotid artery operative procedures (1.6%) performed at the Vascular and Thoracic Surgical Clinic of the "Heidehaus" Municipal Hospital of Hannover and the Surgical Department of the West Attica Hospital of Athens Greece. In 4 cases excision of the aneurysm followed by polytetrafluoroethylene 6-mm graft interposition was performed; 1 patient was treated with end-to-end anastomosis, 1 with ligation of the internal carotid artery (ICA), and 3 with excision followed by interposition of vein graft. Histologic examination showed 7 aneurysms to be atherosclerotic, and a female patient had bilateral microcystic degeneration of the middle layer of the ICA. 519From the