Recently, some clinical studies have suggested that beta-blockers may prevent atrial fibrillation after open heart surgery. In this study, we administered a low dose of landiolol (ultra short acting beta 1-blocker) by continuous infusion postoperatively to evaluate the effects on prevention of atrial fibrillation and hemodynamic stabilization in off-pump coronary artery bypass grafting (OPCAB). A total of 30 patients were given landiolol and studied as landiolol group (L group), and 50 patients who had undergone similar operations before were enrolled as control group (C group). Heart rate was significantly lower in L group without any deterioration of hemodynamics or myocardial disorder. Occurrence of atrial fibrillation within the 1st postoperative week in L group was statistically less than that in C group. Continuous infusion of landiolol in low dose has beneficial effects on hemodynamic stabilization, heart rate control, and prevention of atrial fibrillation in post-OPCAB.