Atrial fibrillation (AF) is a common risk factor for disabling ischemic stroke in the elderly, but it is not clear that its severity is generally worse than that of ischemic stroke due to other etiologies. We reviewed the clinical presentations of patients with acute ischemic stroke admitted between 1990 and 2001. The etiologies of these strokes were also classified using well-established criteria. Of 1,061 patients with acute ischemic stroke, 216 (20.3%) had AF. The frequency of bedridden state was 41.2% in patients with AF, compared to 23.7% in patients without AF (p < 0.0005). Other measures of clinical stroke severity showed similar disparities between these groups. The odds ratio for bedridden state following ischemic stroke due to AF was 2.23 (95% CI = 1.87-2.59, p < 0.0005) by multivariate logistic regression. Ischemic stroke associated with AF is typically more severe than ischemic stroke due to other etiologies, and this increased severity is independent of advanced age and other stroke risk factors. Copyright 2003 S. Karger AG, Basel