BACKGROUND: Atrial fibrillation (AF) is known as a major independent risk factor of cardioembolic stroke. The aim of this study is to compare topographic characteristics of the middle cerebral artery (MCA) territory infarction between in patients with AF and without AF, which explain the cardioembolic infarction as a main manifestation in patients with AF. METHODS: We retrospectively investigated patients with MCA territory infarcts on routine MRI. Thirty-two patients with AF (AF group) and forty-two patients with normal sinus rhythm (NSR group) were compared. Topographic patterns and vascular status of intracranial vessels were analyzed in two groups. RESULTS: In AF group, possible or probable cardioembolic stroke was 78%. The significant stenosis of extra- or intracranial artery was 19% in AF group. The simultaneous involvement of cortical and basal ganglia (p < 0.01) and silent infarctions on contralateral hemisphere (p < 0.01) were more frequent in AF group. The involvement of insular cortex was common in both groups. CONCLUSIONS: In our study, cardioembolism is the most probable cause of cerebral infarction in AF group. Above find-ings may be applied to the proper management of cerebral infarction associated with AF.