Atrial fibrillation commonly occurs after coronary bypass surgery. Most studies suggest that atrial fibrillation develops in approximately 20% to as many as 50% of patients undergoing coronary artery bypass surgery. Over the years, a number of prophylactic regimens have been utilized to prevent atrial fibrillation after coronary bypass surgery. The majority of these studies have used oral agents in various combinations. Few studies have used intravenous agents, and most of these studies have used either beta blockers, calcium antagonists, or class I antiarrhythmic drugs. Recent evidence suggests that intravenous amiodarone may provide safe and effective prophylaxis against atrial fibrillation in many patients undergoing coronary bypass surgery. The evolving data that support such an approach are discussed in this article.