Aim of the study was to investigate role of matrix metalloproteinases (MMP) in assessment of prognosis of repetitive cardiovascular events during hospital stay of patients with ST-elevation (STE) myocardial infarction (MI). We consecutively included into this study 175 patients with diagnosis of STEMI. Content of MMP-1, MMP-3 and MMP-9 in blood serum was measured at admission and on day 12 after onset of disease. Levels of all MMPs on day 12 were 1.1-1.6 times higher than on day 1 of MI (<0.05). Comparison of groups of patients with favorable and unfavorable outcome showed that patients with unfavorable outcome had higher median concentrations of MMP-3 and MMP-9 on day 1; this tendency was maintained on day 12. However these differences were significant only for MMP-9. Compared with patients with favorable outcome levels of this marker in patients with unfavorable outcome were higher by 19.4% (=0.04) on day 1 and by 48.8% (=0.03) on day 12. At logistic regression analysis for MMP-9 and unfavorable outcomes during hospital stay area under ROC-curve did not exceed 0.5. But when only inhospital deaths were considered 2 for MMP-9 (day 1) was 14.3 (<0.0001) while area under ROC-curve was 0.72 (0.64; 0.78; =0.02). Thus in patients with STEMI high concentrations of MMP-9 on day 1 of STEMI can come forward as independent marker of unfavorable outcome during hospital stay.