Plasminogen activator inhibitor was determined in myocardial infarction and re-infarction patients along with other parameters relevant for the Syndrome X, such as triglycerides, HDL-cholesterol and body mass index. Plasminogen activator inhibitor was determined in 58 patients with myocardial infarction and 18 patients with re-infarction as well as in 57 healthy individuals. Significantly higher plasminogen activator inhibitor values were found in re-infarction patients (6.53 +/- 0.39 U/mL) than in myocardial infarction patients (4.32 +/- 0.19 U/mL), whereas the values were significantly higher in both groups in comparison to healthy individuals (2.81 +/- 0.74 U/mL). Triglyceride values were also significantly higher in myocardial infarction (2.05 +/- 0.1 mmmi/L) and re-infarction patients (2.02 +/- 0.99 mmol/L) than in healthy individuals (1.35 +/- 0.58 mmol/L), although the difference between the triglyceride values obtained for myocardial infarction and re-infarction patients was not statistically significant. HDL-cholesterol values for myocardial infarction (1.18 +/- 0.04 mmol/L) and re-infarction (1.14 +/- 0.18 mmol/L) patients were significantly lower than in healthy individuals (1.46 +/- 0.5 mmol/L). However, the difference was not statistically significant between the myocardial infarction and the re-infarction group. The difference in body mass index between myocardial infarction (26.65 +/- 0.39 kg/m2) and re-infarction (25.49 +/- 0.39 kg/m2) patients and healthy individuals (24.45 +/- 3.41 kg/m2) was evidenced.