The purposes of this study are to (1) demonstrate the association of elongations of the internal carotid artery (ICA), that is, kinking, coiling, tortuousity, and angulation, and the neurologic symptoms with high stroke risk; (2) compare the results of the surgical treatment versus the medical treatment alone; (3) contribute to the knowledge of the natural history of these anatomical particularities. From January 1992 to December 1994, 113 patients with ICA kinking, coiling, tortuousity, and angulation were randomized either to surgery (group I, n=55) or not (group II, n=58). Patients, who presented a carotid hemodynamically significant lesion (>60%) at the origin and associated distal elongation were excluded. The groups were comparable with regard to sex, age, risk factors for atherosclerosis, associated diseases, symptoms and anatomic feature of the contralateral ICA. Follow-up was obtained in all patients: it consisted of clinical evaluation and Duplex scan control at 3-month intervals during the follow-up period (6-36 months; average, 23), Histologic specimens were obtained in all surgically treated arteries. Early results were excellent: in group I, no patient died. no patient presented major or minor stroke. Only one patient had an immediate transient ischemic attack (TIA) which spontaneously recovered within 24 hours. All symptomatic patients examined the complete disappearance of clinical signs. There were no late deaths due to stroke and no late major or minor neurologic deficit occurred. All reconstructed ICAs were patent. In group II, three patients experienced a major stroke with hemiplegia due to ICA occlusion. Most of the symptomatic patients (37) of group II remained stable, while seven of them had worsening of symptoms and were referred for surgery. To conclude, all surgically treated patients had the complete relief of preoperative neurologic symptoms; none of the medically treated patients had an improvement. Although there was no statistically significant difference between the two groups with regard to stroke risk, three medically treated patients progressed to total occlusion. This suggests that kinking, coiling, tortuousity, and angulations of the ICA are not merely an anatomic curiosity but a potentially disabling, even fatal condition.