There are many kinds of cardiac complications of hyperthyroidism such as angina pectoris, myocardial infarction, atrial fibrillation, congestive heart failure, heart block and sudden death. While angina is not uncommonly seen in association with hyperthyroidsm, it is rare that myocardial ischemia or infarction may be caused by coronary vasospasm. A 46 year-old man, who had been diagnosed with hyperthyroidism at the first admission, presented with chest pain. The serum thyroid hormone was still elevated. Serial ECGs showed significant ST elevation suggesting transmural ischemia, but coronary angiogram did not reveal any significant lesion. ECG at discharge was normalized without evidence of myocardial infartion. We report this case as an example of severe transmural ischemia with myocardial injury caused by coronary spasm associated with hyperthyroidism.