Endarterectomy is a popular technique for relieving atherosclerotic obstruction of the terminal aorta and iliac arteries. Prior to endarterectomy, the diseased artery is thick-walled, hard, and stiff. After endarterectomy, the artery is thinwalled, soft, and seemingly more compliant. It is remarkable that the frail, almost translucent tissue composing the wall of the endarterectomized vessel is able to withstand arterial pressures and to sustain a suture line which is continually subjected to disruptive tangential forces. Yet endarterectomy, skillfully performed, has proven to be a safe and reliable procedure. To what extent the elastic properties of diseased arterial walls are changed by endarterectomy is largely unknown. The plane utilized in endarterectomy separates the vessel into two concentric tubes: a thick inner tube composed of atheromatous material, intima, and a variable portion of the media; and a thin outer tube composed of media and adventitia. Since the removal of the inner core of