Severe aortic arch atheroma (AAA) is a strong risk factor for ischaemic stroke, but it is unclear whether AAA is a source of cerebral emboli or simply a marker of cerebral atherosclerosis. The purpose of this study was to find out the prevalence of asymptomatic cerebral embolic signals (ES) in patients with acute cerebral ischaemia, AAA and no other potential source of cerebral embolism. Forty patients with anterior circulation ischaemic stroke or transient ischaemic attack (TIA) were prospectively studied using transesophageal echocardiography (TEE) and transcranial Doppler (TCD) scanning within seven days of symptom onset. Patients with a cardiac source of embolism or carotid stenosis > 50% were excluded. ES were detected in 14.3% (2/14) of patients with AAA > or = 4 mm and in no patients with AAA < 4 mm or no AAA (p=0.14). The findings suggest that ES may be associated with severe AAA but their prevalence is low in this setting.