Stroke is the second cause of death and one of the main determinant of disability worldwide. Prevention remains the most important measure for reducing its incidence and mortality. Carotid endarterectomy is one of the possible means for reducing stroke incidence, at least in a subgroup of patients at risk of ischemic stroke. The benefit of carotid endarterectomy has been demonstrated consistently by two large international randomised controlled trials (North American Symptomatic Carotid Endarterectomy Trial, and European Carotid Surgery Trial) in patients with severe symptomatic carotid stenosis. In subjects with asymptomatic carotid stenosis the benefit has been shown by the only available trial (Asymptomatic Carotid Atherosclerosis Study), but proved to be quantitatively less relevant. The benefit is marginal if one considers that only part of stroke events occurring in the territory of an asymptomatic carotid stenosis is preventable by the intervention, since a consistent proportion (almost 50%) of these events are due to other causes (cardioembolism, lacunar infarction). Based on these observations, to obtain a beneficial effect, the perioperative risk should be minimized. Every surgical group should monitor carefully this risk, not omitting minor strokes, that in some cases are functionally relevant. Estimating prevalence and natural history of asymptomatic carotid stenosis in a definite population, the population impact number is expected to be very high, not justifying a widespread screening of the population aimed to identify subjects with asymptomatic carotid stenosis.