The value of routine intraoperative completion arteriography was studied in 260 thromboendarterectomies of the carotid bifurcation in 193 patients. An unacceptable defect was demonstrated in 8% of the endarterectomies. In 11 patients the external carotid artery was found occluded or narrowed distal to its orifice. In three cases the common carotid artery was reopened because of narrowing or remaining plaque or clot. The internal carotid artery was reexplored in seven patients—for complete occlusion in two, and for an intimal flap in five. We have improved our endarterectomy technique by immediate visualization of technical errors.