Abstract: This study was aimed to compare the results of post operative biatrial pacing and IV amiodarone in prevention of AF. In a single blind randomized clinical trial, 210 patients scheduled for elective CABG surgery were randomized either to receive overdrive biatrial pacing, IV amiodarone or no intervention. Incidence of AF postoperatively evaluated. Pacing was successful in 83% of patients and 80% of patients in amiodarone group could receive their drug. Twenty and one patients developed AF. Incidence of AF in pace, amiodarone and control group was 10.7, 5.3 and 17.9%, respectively (p = 0.08). Comparing incidence of AF between pacing and control group, the difference was not significant (p = 0.2), but the difference between amiodarone and control groups was significant statistically (p = 0.03). Patients who developed AF were older but their left ventricular ejection fraction was not different with patients without AF. The ICU stay was higher in patients with AF. Use of IV amiodarone was more effective than biatrial pacing in prevention of post operative AF and we recommend use of this drug in high risk patients.