A 51 year old man presented with unstable angina. Following initial improvement, the patient had prolonged, continuous chest pain resulting in myocardial infarction. During the evolving myocardial infarction, coronary angiography was performed and demonstrated coronary spasm superimposed on a high-grade atherosclerotic lesion. The role of coronary spasm in the etiology of myocardial infarction is discussed. Subsequent aorto-coronary bypass surgery was performed uneventfully.