BACKGROUND: Post-operative atrial fibrillation {AF} after coronary artery bypass graft surgery {CABG} is a frequent complication responsible for high morbidity, a prolonged hospital stay and significant extra-costs. Prevention with prophylactic drug therapy has had limited success, therefore alternative approaches are required. OBJECTIVE: The purpose of our randomized controlled study was to evaluate the efficacy and safety of atrial pacing in the prevention of post-CABG atrial fibrillation by using on-demand atrial pacing via epicardial electrode wire. PA TIENTS AND METHODS: Sixty patients who scheduled for CABG surgery for severe symptomatic CAD were studied prospectively and randomized to no atrial pacing {30 patients. Control group) versus demand atrial pacing at 90 beats per minute {30 patients, paced group), started immediately after operation and continued for 3days. Their ages ranged 40-74 years {mean age 55 ± 6.2 years). The major end point of the study was the development of AF that lasted? one hour duration or required urgent cardioversion. RESULTS: The overall incidence of A.F among the studied population was 26.75% { l6patients} during the study period. It was significantly lower in paced group versus non paced group (13.3% VS 40%, p<O.05 ). The incidence of AF was found to be higher in old (?60y) than young patients (<60 y) (77.8%VS 23 .8%, p<0.05). The incidence of AF was also higher among patients with LA size ? 4cm. than those with LA size <4cm. (57.1% VS 25%, p<0.05).The incidence of AF among patients with prior MI was 62.5% VS 34.5% in those patients with such histoi {p<O.05 }. The pacing was not associated with added risk except for musculo-skeletal discomfort due to electrical stimulation in some patients. CONCLUSION: Our study provides preliminary evidence of a significantly decrease in the incidence of post-CABG AF using on demand atrial pacing. This technique is effective and safe with no added risks and can be used in all patients especially those at high risk of post-CABG AF.