Inflammation plays an important role on every stage of atherosclerosis. Myeloperoxidase (MPO), a leukocyte-derived enzyme that participates in the innate immunity, probably is involved in many stages of atherothrombosis. According to the recent studies, MPO is related with unfavorable outcome in patients with chest pain and acute coronary syndromes. Its role in prediction of outcomes after ST-segment elevation myocardial infarction (STEMI) remains unclear. The aim of the study was to assess if elevated MPO level is a predictor of long-term adverse cardiac events in patients with STEMI treated with primary percutaneous coronary intervention (pPCI).