To improve prognosis in acute coronary syndrome, new clinical applications in terms of diagnosis, risk stratification, and treatment strategies are still under investigation. Ischemia-modified albumin was one of the novel markers of myocardial ischemia. In our study, we aimed to determine the prognostic significance of the albumin cobalt binding capacity test in patients with acute coronary syndromes. We compared the ischemia-modified albumin levels of patients with acute coronary syndrome with those of patients with stable coronary artery disease and those of normal individuals and found them to be significantly higher in the first group (P<0.05). A cutoff value of ischemia-modified albumin of 477 U/ml was found by using receiver operating characteristic curve analysis. Mortality in groups of patients whose ischemia-modified albumin levels were above 477 U (50%) was found to be significantly higher than in those whose levels were below 477 U (8.3%) (P<0.05). The sensitivity and specificity of the cutoff value, 477 U/ml, for the 1-year mortality were found to be 70 and 82%, respectively. Using the Cox regression model the relation of albumin cobalt binding capacity test results with mortality was statistically significant (beta=1.013, confidence interval 95%, P=0.01) and independent of the existence of hypertension, diabetes, and advanced age. In conclusion, ischemia-modified albumin was found to be significantly related to 1-year mortality. Prognostic significance of ischemia-modified albumin should be evaluated in large populated and randomized study groups. Afterwards, ischemia-modified albumin could be used in risk stratification modality in patients with acute coronary syndrome.