A 73-year-old male patient with a past history of hypertension and atrial premature contraction underwent endoscopic restoration of the left bubonocele. Sinus rhythm was confirmed by preoperative electrocardiography, but paroxysmal atrial flutter developed when abdominoscopy was started. Continuous administration of landiolol hydrochloride at a dose of 0.005 mg kg(-1) min(-1) after a loading dose of 0.04 mg kg(-1) min(-1) for 1 min resulted in control of heart rate without a decrease in blood pressure. Atrial flutter was converted to sinus rhythm 3 min after the start of administration. Landiolol hydrochloride was administered continuously until the morning of the following day and sinus rhythm was maintained postoperatively.