Background: In early phase of acute chest pain, diagnosis of acute coronary syndrome (ACS) is often difficult in emergency department (ED) due to non-diagnostic ECG and cardiac markers. Troponin and CK-MB is sensitive and specific for the detection of myocardial damage but may not rise during early phase of ischemia and reversible myocardial ischemia. Ischemia Modified Albumin (IMA) has recently been shown to be an early sensitive and biochemical marker of ischemia.Objective: The aim of this study was to compare the diagnostic value of IMA to that of cardiac markers and ECG in patients suspected ACS in ED.Method: We enrolled consecutive 72 patients presenting to the ED suspected ACS within 6 hours of chest pain. At presentation, a 12-lead ECG was recorded and blood taken for IMA and cardiac markers. The diagnosis of ACS was based upon clinical findings and results of serial ECG/troponin and coronary angiography performed before discharge. Receiver Operator Characteristic (ROC) curve analysis determined the ideal diagnostic cutoff of IMA for ACS was calculated.Results: The ACS was diagnosed in 53/72. There was no correlation between IMA and necrosis markers. The ROC curve area for the IMA test was 0.90 (95 % confidential interval, 0.78-1.00, p=0.001). At a cutoff value of 95.5 U/mL, the sensitivity, specificity and negative predictive value for ACS were 96%, 79% and 90%, respectively. Conclusions: IMA is highly sensitive and negative predictive value for the diagnosis of ACS in patients presenting within 6 hours after symptoms of suspected ACS.