A 57-year-old man was admitted to the emergency room because of a chest pain for one hour that radiated to the shoulder and arm. The pain was similar to the chest pain he usually had experienced, except for the one hour's duration. Six months before admission, he experienced a chest pain with a squeezing nature, causing central, substernal discomfort. The pain lasted 2 to 5 min. The pain usually occurred between 2 a.m. and 7 a.m. during sleeping, once or twice per month, and was not caused by exertion. He was a heavy smoker. The blood pressure was 100/60mmHg and the pulse rate was 85/min. The remainder of physical examination was normal. Electrocardiogram showed tall and tented T waves in lead V1 through V4. Fourteen minutes after admission, the electrocardiogram changed and showed a left bundle branch block pattern with an ST elevation and tall T waves without P waves in lead V1 through V4. This rhythm was accelerated idioventricular rhythm. The electrocardiogram obtained 23 minutes after admission showed a right bundle branch block pattern with an ST elevation and tall T waves without P waves in lead V1 through V4. He was treated for variant angina with sublingual and intravenous nitroglycerine, with complete resolution of the chest pain. The electrocardiogram obtained after resolution of the chest pain was normal. At the emergency room, the creatine kinase(CK) level was 144 U/L (normal, 55~170) and the troponin T level was 0.033 ng/ml (normal, 0.000~0.100). Eight hours after admission, the CK level was 598 U/L. The coronary angiogram, performed on the fourth hospital day, showed 99% spasm on the proximal left anterior descending artery by intravenous ergonovine provocation test. He was treated with long-acting nitrate and calcium antagonist, and experienced no more chest pain. The final diagnosis of this patient was acute myocardial infarction by variant angina.