We investigated prognostic value of myeloperoxidase level (MPO) and activity of myeloperoxidase at short-term and long-term prognosis in patients with acute coronary syndrome (ACS). The study included 93 patients with ACS. At first 24 hours the MPO and activity of MPO were measured. We divided patients in two groups according primary end point (death from cardiovascular causes, nonfatal myocardial infarction, refractory angina and need for emergency myocardial revascularization). The activity of MPO at first 24 hours and MPO level at 7 day were significantly higher in patients with primary end point (p<0,05). In patients with MPO level higher than 42,4 ng/ml at 7 day is associated with increasing of hazard ratio for the primary end point in 1,81 times (95% CI 0,35-3,27; р=0,015). It was concluded that high MPO level could identify patients with worse prognosis after ACS.