In this study we performed a retrospective chart review to evaluate the efficacy of short-term postoperative oral amiodarone therapy on postoperative atrial fibrillation (POAF) after coronary artery bypass surgery. The incidence of POAF in 372 patients (60.6%) without prophylactic amiodarone therapy was compared with that in 240 patients (39.4%) receiving the medication immediately after the surgery. Patients who received prophylactic amiodarone developed significantly less POAF than those without prophylactic treatment (17.0% versus 25.9%, P = .01), with relative and absolute risk reductions of 0.7% and 8.9%, respectively. Postoperative oral amiodarone therapy is simple to administer and may be a valuable adjunct therapy for patients after coronary artery bypass surgery.