The relation between C-reactive protein, an inflammatory marker, and thromboembolic risk factors was investigated in 104 patients with atrial fibrillation and found that patients with transesophageal echocardiography identified thromboembolic risk factors had greater C-reactive protein levels than those without (1.00 vs 0.302 mg/dl). C-reactive protein also correlated with clinical stroke risk factors. Increased C-reactive protein levels were also independently associated with transesophageal echocardiographic thromboembolic risk factors.