Angina pectoris is a state of coronary artery disease, If the myocardial oxygen consumption (MVO₂) is greater than the coronary blood flow from any cause, myocardial ischemic damage will almost always follow due to lack of oxygen. The authors experienced cardiac arrest in a patient of unstable angina pectoris during induction of general anesthesia. External cardiac massage was carried out and essential drugs were given immediately, but they did not restore the normal sinus rhythm. We then gave 100 J. of DC countershock at first with failure, then another 200, 300 and 400 J. were given intermittently under the observation of continuous ECG monitoring. Thereafter, complete normal sinus rhythm was restored without any dysrrhythmias, and the patient regained consciousness from the stuporous state due to the induction agents. Because of the light premedicants and also the light induction agents and pancuronium during intubation, the patient's heart could not endure any more in this state of oxygen lack. Patients who have serious organic heart diseases should indeed be prepared with great caution before and during an anesthesia.