Previous randomized clinical trials have reported the advantage of surgical treatment in reducing the risk of stroke compared with medical therapy alone in asymptomatic carotid artery stenosis. However, recent advances in medical treatment have resulted in a decline in the risk of stroke in patients with asymptomatic carotid artery stenosis treated medically. Therefore, we aimed to assess the surgical and long-term outcomes of patients with asymptomatic carotid artery stenosis in our hospital, and to identify high-risk patients. Between August 2006 and December 2013, 216 consecutive carotid artery revascularization procedures with carotid endarterectomy (CEA; 129 procedures) or carotid artery stenting (CAS; 87 procedures) for carotid artery stenosis were performed in our hospital. There were 123 patients with asymptomatic carotid artery stenosis (71 CEAs and 52 CASs) and 93 patients with symptomatic carotid artery stenosis (58 CEAs and 35 CASs). The main indications for surgical treatment of asymptomatic carotid artery stenosis were as follows: mobile plaque (4.1%), severe stenosis (≥80%) (41%), progression of stenosis (21%), restenosis (4.7%), need to lower the perioperative risk of another surgery (8.1%), and vulnerable plaques on carotid artery ultrasound or magnetic resonance imaging. Perioperative complication rate (any stroke or death within 30 days) was 1.6% in the asymptomatic group and 5.4% in the symptomatic group, which was not significantly different. The average annual estimated 5-year risk of perioperative events and ipsilateral stroke was 0.67%, and that of perioperative events and any stroke was 1.4% in asymptomatic stenosis, which were comparable to the best results of medical treatment. Our findings showed that aggressive surgical treatment for asymptomatic carotid artery stenosis in high-risk patients may reduce the risk of further stroke. Further studies are needed to clarify this point.