The true incidence of recurrent carotid stenosis is unknown. Most reports provide only anecdotal data. Reported incidences, which range from 0.6% to 9.8%, reflect the care with which the search for recurrent stenosis was made by individual reporters. Early restenosis occurring within less than 24 months is characterized by a fibrous hyperplastic reaction, whereas stenoses occurring beyond this time are usually caused by typical atherosclerotic lesions. Although no clear risk factors can be identified, surgical trauma and inadequate endarterectomy are likely predisposing causes. Reoperation is technically more difficult and a patch graft, preferably vein, is often necessary. Careful postoperative evaluation and a search for the possibility of recurrent stenosis is recommended, especially in view of the increasing frequency of prophylactic carotid endarterectomy.