The DD genotype of angiotensin converting enzyme gene has been reported to be a risk factor for myocardial infarction. However, this association has not been confirmed in some study populations. We hypothesized that the discrepancies between these studies may be due to variations in the definition of ischemic heart diseases. According to the genotype of the ACE gene, we analyzed the profiles of 320 patients who underwent coronary angiography for suspected ischemic heart disease. We found that the II genotype of the ACE gene was associated with a longer period of time between the first anginal pain and the onset of myocardial infarction. Because higher ACE has been reported to be associated with higher plasminogen activator inhibitor-1 activity, our observation suggests that the genotype of the ACE gene is a marker of fibrinolytic activity.