We report five patients who developed intraoperative myocardial ischemia but were treated successfully with nicorandil. Case 1; An 84 year-old male underwent emergent laparotomy and ileolysis under inhalational plus thoracic epidural anesthesia. During his emergence from anesthesia, arterial pressure and heart rate increased abruptly due to excitement, leading to ST-T depression on V5 lead. Bradycardia and hypotension developed subsequently. Immediately after i.v. injections of nicorandil 4 mg and atropine 0.3 mg, ST-T change and hemodynamics improved dramatically. Case 2; A 67 year-old male underwent esophagectomy under inhalational plus thoracic epidural anesthesia. Following the completion of surgery, elevation of ST-T developed suddenly on lead II, though hemodynamics were not compromised. ST-T elevation disappeared immediately after nicorandil 6 mg and continuous infusion of nitroglycerin (TNG) was initiated. Case 3; A 71 year-old female underwent aortic valve replacement under high-dose fentanyl anesthesia. Shortly after starting cardiopulmonary bypass (CPB), ST-T segment on leads II and V5 was elevated suddenly. This was accompanied by severe pulmonary hypertension suggestive of severe left ventricular failure. Shortly after nicorandil 4 mg via a pulmonary artery (PA) catheter, ST-T segment returned to the baseline and pulmonary arterial pressure was normalized. Case 4; A 61 year-old male underwent coronary revascularization under high-dose fentanyl anesthesia. During weaning from CPB, elevation of ST-T segment occurred on leads II and V5. ST change improved, responding to nicorandil 6 mg en bolus via a PA catheter. Case 5; A 67 year-old male underwent coronary revascularization under high-dose fentanyl anesthesia. He was unable to be weaned from CPB for several hours because of frequent and repeated attacks of ventricular tachycardia and ventricular fibrillation. The arrhythmia did not respond to various kinds of treatments including intra-aortic balloon pumping and continuous infusions of inotropes, anti-arrhythmic drugs and anti-anginal drugs. In spite of repeated intracoronary injections of TNG, graft flow to the left anterior descending branch remained low at 40 ml.min-1. After an intracoronary injection of nicorandil 1 mg, however, blood flow increased to 100 ml.min-1, resulting in a marked reduction in frequency of ventricular arrhythmia. The patient came off bypass successfully. In each case, intraoperative myocardial ischemia was treated successfully with nicorandil. Neither hypotension nor arrhythmia resulted from its bolus injection. Nicorandil might be a useful therapeutic tool for myocardial ischemia during anesthesia.