Background & Objectives: Atherosclerotic stenosis of carotid territory is the most common cause of ischemic stroke. A higher frequency rate of intracranial arterial stenosis in African and Far East races has been reported.

 Methods: This double center and prospective study was carried out in 304 geriatric ischemic stroke patients admitted in Mackenzie Hospital, Canada and the same number of geriatric ischemic stroke patients with similar sex ratio admitted in Valie-Asr Hospital, Birjand during 2003-2005. The cause of brain infarction in carotid territory was made by neurologists was vasular origin. All of the patients underwent transcranial and carotid doppler studies based on the standard method by a neurosonologist. Topography of arteriosclerotic stenosis in bilateral Internal Carotid Artery (ICA) territories was determined. Fisher exact test served for statistical analysis and p<0.05 declared as significant.

 Results: In Iranian group 71 patients (23.3%) and in North American group 83 patients (27.3) had extracranial ICA stenosis without a significant difference p=0.3, df=1, OR=0.81, 95%CI(0.56- 1.17). Sever ³ 70% extracranial ICA stenosis was found in 14 Iranian patients (4.6%) and 23 North American patients (7.5%) without a significant difference . p=0.17, df=1, OR=0.59, 95%CI(0.3-1.77). In Iranian group, 14 cases (4.6%) and in North American group 5 cases (1.6%) had intracranial ICA territory stenosis which had a significant difference p=0.038, df=1, OR=2.9, 95%CI(1-8.1). Mixed intracranial and extracranial ICA territory stenosis was found in 2 Iranian and 1 North American patients.

 Conclusion: Atherosclerotic stenosis of intracranial ICA territory is more common in Iranian than in North American populations.