The electrocardiograph (ECG) is now used as a routine monitor during anesthesia and operation. Cannard and co-workers showed the value of the ECG in diagnosing rhytm disturbances during anesthesia.1Standard limb lead II is usually observed because its axis parallels the electrical axis of the heart and the P wave is usually easily seen.2,3In recent years, coronary-artery disease has become the number one health problem in the United States, Patients coming for all types of surgical procedures have significant coronary-artery disease, and many have histories of acute myocardial infarction or angina peeturis. In these patients, the ECG should be used to identify myocardial ischemia during the stress of anesthesia and operation, as well as for arrythmia recognition.The graded ECG exercise test is routinely used by cardiologists to diagnose coronary-artery disease. Blackburn showed that S9 per cent of the ST-seginent information contained in the conventional 12-lead exercise ECG is found in lead V3.1Therefore, we began monitoring lead V3, along witfi leads I, II, III, AVR, AVL, AVF. in all patients with known coronary-artery disease. Below, we present three cases in which significant myocardial ischemia occurred intraoperatively and was observedonlyin lead V3. This information led to early treatment of the ischemic episodes.