Coronary bypass surgery is performed on over 400,000 patients each year in the United States. Atrial Fibrillation (AF) is the most common complication after bypass surgery. The significance of its occurrence lies not only in the potentially dangerous and physiologic derangement to patients, but also in the impact it has on the utilization of health care resources. Several clinical observations suggest that the occurrence of atrial fibrillation after bypass surgery has some unique features related to the perioperative circumstances. Numerous therapies, both pharmacologic and non-pharmacologic have been tested to prevent this tenacious problem. Its persistence continues to intrigue cardio-thoracic surgeons, cardiologists, anesthesiologists and the insurers alike. In this review we discuss the published literature on postbypass AF, with a special emphasis on pharmacologic prevention.