There is a low incidence of myocardial infarction (MI) for those under 45 years old. Many risk factors have been described for MI. Some risk factors may be especially important for younger people. A 23 year-old young patient with acute anterior myocardial infarction and no prior symptoms was presented. The patient was treated with precutaneous transluminal coronary angioplasty (PTCA). Although we investigated the risk factor in detail. We couldn’t find any risk factors apart from cigarette smoking. The patient had high HDL-cholesterol level and as it is known this eliminate one positive risk factor. The occurence of MI in a patient with high HDL cholesterol who has no other risk factors apart from cigarette smoking is a remarkable sample that cigarette smoking is an extremely important risk factor for young patients and that HDL cholesterol level is not sufficient enough to prevent the negative effects of this risk factor.