In patients with established ischemic heart disease, prospective cohort studies have indicated that plasminogen activator inhibitor (PAI-1), the inhibitor of the fibrinolytic system, may predict cardiovascular events. So far, there have been no primary prospective studies of PAI-1.The aim of the present study was to test whether plasma levels of PAI-1, tissue-type plasminogen activator (tPA), von Willebrand factor (vWF), and thrombomodulin (TM) could predict the occurrence of a first acute myocardial infarction (AMI) in a population with high prevalence of coronary heart disease by use of a prospective nested case-control design. Mass concentrations of PAI-1 and tPA were significantly higher for the 78 subjects who developed a first AMI compared with the 156 references matched for age, sex, and sampling time; for tPA, this increase was independent of smoking habits, body mass index, hypertension, diabetes, cholesterol, and apolipoprotein A-I. The ratio of quartile 4 to 1 for tPA was 5.9 for a patient to develop a first AMI. The association between tPA and AMI was seen in both men and women. Increased levels of vWF were associated with AMI in a univariate analysis. High levels of TM were associated with AMI in women but not in men.The plasma levels of PAI-1, tPA, and vWF are associated with subsequent development of a first AMI; for PAI-1 and tPA, this relation was found in both men and women. For tPA but not for PAI-1 and vWF, this association is independent of established risk factors.