Background: The optimal therapeutic strategy of high-risk Postoperative Atrial Fibrillation (POAF) remains to be less well defined so objectives was to investigate the efficacy of prophylactic metoprolol versus low-dose sotalol regimens for the prevention of high-risk Atrial Fibrillation (AF) following coronary artery bypass surgery (CABG). Methods: 113 consecutive Patients referred for CABG were randomly assigned to either metoprolol or low-dose sotalol regimen. The primary end-point was the frequency of POAF during 6-week follow up. Results: Out of 113 patients enrolled, 52.2% % were assigned to receive metoprolol while 44.8% were assigned to receive sotalol. The frequency of POAF at follow up was significantly higher among the metoprolol group (59.3 % versus 50 %; P=0.017). The predictors of POAF were: age > 60 years; low EF%; and sotalol. "sotalol was protective" - for sotalol; OR= 0.49%; (95% CI=0.25 -0.97); P=0.02. Length of hospital stay was significantly higher among the metoprolol (7.51.3 % versus 6.11.2; P<0.001), while other clinical end-points (deaths, stroke, HF, angina, and major dysrhythmias) did not differ significantly among the two groups. Conclusion and recommendation: Prophylactic low-dose sotalol is superior to metoprolol in prophylaxis of high-risk POAF. However, Larger scaled prospective multicenter randomized trials are needed for confirming our favorable results of using prophylactic low dose sotalol in high risk POAF.