Aortic arch atherosclerotic lesions can cause ischemic cerebrovascular disease (ICVD). The association between carotid and aortic atherosclerosis was examined, and it was investigated whether noninvasive carotid evaluation aids in the identification of aortic lesions as potential ICVD risk. The subjects comprised 147 patients with ICVD who had undergone carotid ultrasonography and transesophageal echocardiography. Carotid and aortic arch atherosclerosis was evaluated by measuring the maximum intima - media thickness (IMT), with aortic IMT of at least 4 mm, mobile plaques and/or ulcers defined as complex aortic lesions with potential ICVD risk. Carotid IMT was linearly associated with aortic IMT (r=0.53, p<0.001), and the association was independent of traditional cardiovascular risk factors (β =0.36, p<0.001). Also, each 1 SD greater carotid IMT was associated with 4.2-fold (95% confidence interval: 2.5-7.0) higher likelihood of complex aortic lesions, with the likelihood little modified when controlling for cardiovascular risk factors. In particular, complex aortic lesions were found in 78% of patients with the highest carotid IMT tertile, compared with 14% of those with the lowest tertile (p<0.05). Based on these findings, carotid atherosclerosis is associated with aortic atherosclerosis, representing a risk factor for aortic lesions that are a potential ICVD risk. (Circ J 2003; 67: 597 - 600)