Aim: Acute coronary syndrome (ACS) is a clinical condition that exists signs and symptoms with acute chest pain and myocardial ischemia. Ischaemia-modified albumin (IMA) is a new diagnostic biochemical marker for acute coronary syndrome. It has been proposed that reactive oxygen species which occur in ischemia lead the formation of IMA. The aim of our study is to determine the levels of new cardiac ischemia marker IMA in ACS, the effect of smoking that is an event that leads to the formation of reactive oxygen species on IMA levels and the role of this effect on the interpretation of IMA results. Material and Method: 63 patients who met the acute coronary syndrome diagnosis criteria with no elevations of Troponin I, and 61 age-matched control subjects were included in this study. Ischemia-modified albumin levels were determined with a colorimetric method. Results: Serum ischemia-modified albumin levels in the patient group were significantly higher compared to the control group (0.644 ± 0.168 vs. 0.534 ± 0.116, respectively). Although smokers have higher ischemia-modified albumin levels in the control and patient groups, this difference was not statistically different. Discussion: This is the first study evaluating the relationship between smoking and ischemia-modified albumin levels in acute coronary syndrome. In this study, smoking was found to have no effect on ischemia-modified albumin levels in patients with acute coronary syndrome.