Coronary artery injury rarely occurs after blunt chest trauma, but it can lead to extensive myocardial infarction and be frequently overlooked. A 16-yr-old man was presented with comatose mental state and rapid respiration rate. He ran into guard rail while riding a motorcycle. In routine examination, his electrocardiogram showed Q wave and 2 mm ST segment elevation in all precordial leads, I and aVL. The cardiac enzymes were also elevated: creatine kinase (CK)-MB was 300 U/L, and cardiac specific troponin I was 5.7 ng/mL. Two-dimensional echocardiography showed anteroseptal akinesia with severely depressed left ventricular function, ejection fraction of 28%. He could not receive any anticoagulation or thrombolytic therapy because of his brain lesion. Three weeks later, his mental state improved. A diagnostic coronary angiogram revealed total occlusion in the proximal left anterior descending artery (LAD) with collaterals from the right coronary artery and left circumflex artery. We successfully performed a percutaneous coronary intervention for the LAD lesion, and the final angiogram showed a good coronary flow without residual stenosis.