Plasma level of von Willebrand factor (vWF) is a useful marker not only for endothelial dysfunction, but also for left atrial thrombogenesis. We measured plasma levels of vWF antigen and other coagulation and fibrinolysis markers in 183 consecutive patients with acute ischemic stroke and compared these data between patients with and without atrial fibrillation (AF). vWF correlated with severity, outcome, and infarct size and were significantly higher in the AF group than in the non-AF group. The positive correlations of vWF with plasmin-alpha2 plasmin inhibitor complex and soluble fibrin monomer complex, and higher levels of vWF in patients with than without spontaneous echo contrast, indicate thrombogenesis in the left atrium. Plasma levels of vWF may reflect thrombogenesis in patients with AF.