Cerebrovascular mortality represents 25% of all cardiovascular mortality. Defining the pathological mechanism of an episode of ischemic stroke is important for epidemiological, prognostic and overall therapeutic purposes. About 1/4 of ischemic strokes are defined as being of unknown cause. The use of transesophageal echocardiography for studying the aortic arch and thoracic aorta, revealed that aortic atheroma can be considered as an embolic source. Retrospective studies documented a significant prevalence of atheroma >4 mm in the aortic arch in patients with previous stroke (15%); while prospective studies documented an increased risk for cardiovascular events in patients with plaque of =/> 4 mm in thickness at the level of the thoracic aorta compared with controls without these lesions: in particular, the incidence of recurrent stroke is 12%/year, while the incidence of cardiovascular events is 26%. Plaques defined unstable and at risk of embolic event are protrudent, >4 mm in thickness, without calcification and have on their surface mobile thrombus. Embolization from a protrudent atheroma can have a iatrogenic cause, that is cardiac catheterization or placement of an intra-aortic balloon- pump or during cardiopulmonary bypass. The management of the subject with aortic atheroma is not well defined. Encouraging dates with the use of statins are from a recent meta-analysis also anticoagulant treatment versus antiplatelet treatment, reduced incidence of stroke in a significant manner. The surgical therapy of aortic endoarterectomy, has, at this moment, a limited indication, because is not without risk. Transesophageal ecocardiography is a method of choice for the study of the aortic atheroma and it should be done in every patient with stroke by unknown cause.