In the past few years evidence that atherosclerotic disease of the aortic arch is probably an underestimate source of emboli, particularly moving thrombi in the lumen, has accumulated. Pathological studies, and more recently transesophageal echocardiographic studies, have shown that atherosclerotic disease of the aortic arch is an independent risk factor for ischemic stroke and carries a high risk of recurrent vascular events. It could account for a more or less part of brain infarcts of unknown cause, with no carotid or cardiac source of emboli. This location of atherosclerotic disease is rare under 60 years of age. It mainly involves patients older than 60 years of age, and is frequent in patients in their eighties. Transesophageal echocardiography is accurate, safe and well tolerated for the examination of the aortic arch, even in elderly patients. Practical implications for patients and future clinical trials are important. As it is a strong marker for recurrent vascular events, the risks and benefits of different therapeutic options should now be evaluated in randomised trials.