This study examines the degree and location of vessel wall geometric changes after carotid endarterectomy—vein patch reconstruction. The external diameters of the proximal common carotid, common carotid bulb, and internal carotid arteries were measured during operation with a caliper after 349 carotid endarterectomies. There were 309 saphenous vein reconstructions, 31 synthetic patch reconstructions, and 9 primary closures. One or more B-mode ultrasound studies with cross-sectional views for common and internal carotid cursor measurements were performed from 3 months to 5 years after operation. The intraoperative-to-postoperative common carotid diameters were unchanged for the three types of reconstructions. The internal carotid diameters increased 20% to 30% for both the vein and synthetic patched arteries. This dilation was present at 3 and 6 months and progressed slightly over 5 years. Wall thickening ≥1 mm was present in 62% of the carotid endarterectomies, with concentric stenosis in 3% and eccentric stenosis in 59%. Eccentric stenosis was present at 3 to 6 months, located on the endarterectomized posterior-medial wall of the common and internal carotid arteries, was always less than 50%, and changed very little over 5 years. No aneurysms or internal carotid occlusions were identified. Carotid endarterectomy—vein patch reconstruction results in early, mild, nonaneurysimal dilation of the internal carotid patched segment, frequent mild eccentric restenosis, and rare hemodynamically significant concentric restenosis.