A 62-year-old man with supraventricular/ventricular tachycardia associated with myocardial infarction developed tachycardia during beating coronary artery bypass grafting (CABG). Intravenous administration of an ultra short acting beta-blocker, landiolol hydrochloride, controlled heart rate and improved tachyarrhythmia without significant change of blood pressure. Landiolol hydrochloride is effective and useful for the treatment of tachyarrhythmia during beating CABG.