The International Carotid Stenting Study examined 1713 patients across 50 centers with symptomatic carotid stenosis (50% or greater) who were randomized to angioplasty and stenting vs endarterectomy in a 1:1 ratio. Patients were followed at 30 days, 6 months, and annually for 10 years with carotid Doppler studies. In the 1530 patients with adequate follow-up, 5-year cumulative risk of at least moderate restenosis (> 50%) was 40.7% after stenting and 29.6% in endarterectomy patients (p<0.0001). No significant difference was seen in the frequency of severe restenosis (>70%), occurring in 10.6% of the stented patients and 8.5% of the endarterectomy patients. In both treatment groups combined, patients with at least 50% restenosis were at a higher 6-year risk of ipsilateral stroke (6.9% vs 2.5% p=0.002), though increased risk of stroke with restenosis in the stenting group alone did not reach significance (7.8% vs 3.8%, p=0.154). There was no significant difference in the 6-year risk of ipsilateral stroke between interventions. This study provides evidence that long term follow up is indicated following stenting and endarterectomy for carotid stenosis.