Dear Editor-in-Chief: Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice. Patients with AF have increased rates of mortality and are strongly at greater risk of stroke (1). Despite strong recommendation of anticoagulant therapies in AF patients, real world data demonstrates low adherence of physicians to prescribe anticoagulant medications for AF patients (2, 3). A study was designed to compare the practice of anticoagulant therapies in AF patients in two major university hospitals affiliated with Tehran University of Medical Sciences (TUMS) in Tehran with available guidelines.