Objective: The use of matrix metallopeptidase-9 (MMP-9) in patients with acute myocardial infarction with ST-segment elevation (STEMI) after percutaneous coronary intervention (PCI) as a prognostic indicator has a lot of gaps and the medical community has very limited experience with it. The study aimed to evaluate the prognostic role of MMP-9 in STEMI patients after successful revascularization within a 12-month follow--upperiod.Material and method: 88 patients met the inclusion criteria and had no exclusion criteria diagnosed with STEMI who underwent primary PCI were enrolled in the study. 66 (75.0%) were men, with a mean age of 60.84 +/- 9.68 years. A follow-up period was 12 months. The combined endpoint was used and it included the occurrence of heart failure, which required hospitalization, cardiovascular death, recurrent myocardial in-farction, acute cerebrovascular event. The level of MMP-9 was determined by ELISA.Results: Kaplan-Meier curves analysis showed signifi cant association between increased MMP-9 and stu-died combined endpoint, p = 0.0229. The patients with MMP-9 levels over 201.7 ng/ml had signifi cantly more endpoints. Univariate regression analysis found that MMP-9 was indicated as independent variable for unfavorable outcome with odds ratio (OR): 1.017, 95 confi dence interval (CI) %: 1.001-1.033, p = 0,037. The multivariate logistic regression analysis showed that MMP-9 (OR: 1.019; 95% CI: 1.005-1.033; p = 0.009) together with fasting glucose (OR: 1.246; 95% CI: 1.010-1.538; p = 0.040) and leucocytes (OR: 0.751; 95% CI: 0.558-1.011; p = 0.057) remained signifi cant independent predictors of combined endpoint in the studied subjects after adjusting other investigated confounders, age, sex, BMI, lipid and glucose profi les. Conclusion: There is a signifi cant relationship between adverse events and elevated MMP-9 levels in STEMI patients after PCI. MMP-9 was evinced as a highly sensitive marker for predicting the adverse course of the disease in patients with STEMI during the one-year follow-up.