Aim — we estimated malondialdehyde (MDA) and thiobarbituric acid-reactivity in patients with acute coronary syndrome (ACS). We also evaluated the prognostic value of these markers in short-term prognosis in patients with ACS.  Material and methods. We enrolled 93 patients with ACS. The MDA and thiobarbituric acid-reactivity were measured at first 24 hours and 7 days after admission. We divided patients in two groups according to primary end point (death from cardiovascular causes, nonfatal myocardial infarction, refractory angina and emergency revascularization within 30 days after ACS). Results. In patients with ST-elevation myocardial infarction the MDA level was significantly higher than in those with other forms of ACS (p=0.019). MDA level did not differ between groups. In patients with thiobarbituric acid-reactivity level higher than 112 nmol/ml at the 7 day hazard ratio of nonfatal myocardial infarction was 2,4 (95% CI 1.04—4.78; р=0.046). Conclusion. Lipid peroxidation end products (MDA and thiobarbituric acid-reactivity) might be used for risk assessment in patients with ACS.