A 26-year-old male suffered sustained chest pain. Electrocardiogram showed ST-segment elevation in the anteroseptal wall and reciprocal ST-segment change in the inferior wall. The troponin-I level and the white blood cell count were elevated. We gave a diagnosis of acute myocardial infarction. He underwent urgent coronary angiography, which revealed 90% diffuse stenosis in the middle right coronary artery and total occlusion in the proximal left anterior descending coronary artery (LAD). Since the electrocardiogram indicated that the culprit lesion was in the proximal LAD, we performed percutaneous coronary intervention. The coronary flow in the LAD was classified as thrombolysis in myocardial infarction trial 3. His coronary risk factors were obesity, smoking, family history, hypertension and diabetes, in addition to heterozygous familial hypercholesteremia (FH). Herein, we describe the case of a young patient with acute anteroseptal myocardial infarction and discuss the potential importance of controlling cholesterol levels in FH.