Surgical therapy has been applied in the treatment of atrial fibrillation for almost two decades. At present, the most commonly used approach is the maze operation developed by Cox. In this operation, atrial fibrillation is prevented by critically located incisional lines. Currently, these lines also are drawn during operation using cryoablation or radiofrequency current. To document the value of the maze operation, randomized studies, not only on arrhythmia prevention but also on atrial transport function and thromboembolic complications, should be performed.