A 45-year-old Turkish male patient was admitted to our hospital for an acute myocardial infarction. He had suffered two previous acute myocardial infarctions 5 and 6 years earlier. Coronary angiography performed after the previous two acute myocardial infarctions had shown normal coronary arteries and coronary vasospasm had been suspected. The patient was treated with thrombolytic therapy (rt-PA) during the last coronary event. Five days after the current admission, the patient had postinfarct angina and underwent coronary angiography, showing only a nonobstructive lesion with irregular ulcerated edges in the left anterior descending artery after the first diagonal branch. Subsequent intravascular ultrasound confirmed the presence of an atherosclerotic lesion with plaque dissection. Stenting of this lesion was performed with successful relief of on-going chest pain. Intravascular ultrasound can provide important diagnostic information in patients presenting with acute coronary syndromes in the absence of severe angiographic stenosis. Identification of plaque dissection at mildly stenotic lesions provides pathophysiologic insights that may have therapeutic implications. However, the optimal treatment for such lesions is not known.