The case of a 20-year-old man with acute myocardial infarction is described. He developed acute myocardial infarction on 11 July 1995. An emergency coronary arteriogram revealed total occlusion of the proximal left anterior descending coronary artery. Reperfusion was achieved by intracoronary injection of 6.4 x 10(6) units of native tissue plasminogen activator, which left multiple, angiographically identifiable, thrombi in the left anterior descending coronary artery. As a coronary angiogram 28 days after the onset showed no organic stenosis or wall irregularity, we conducted an ergonovine provocation test. The infusion of 32 micrograms of ergonovine into the left coronary artery provoked diffuse, high-grade vasospasm. The patient's medical history showed that he had been diagnosed as having Kimura's disease when he was 19 year-old. Additionally, he had exhibited persistent eosinophilia of unknown origin for 10 months or more. Thus, his condition was consistent with a diagnosis of hypereosinophilic syndrome (HES). This is the first report to document angiographically the presence of acute coronary obstruction in a patient with HES. The acute coronary occlusion was thought to be related to coronary artery vasospasm.