Objective: Troponin I (TnI) is an important component in the diagnosis of acute coronary syndrome (ACS) patients and their management. The use of high- sensitive TnI test enables the detection at low levels of TnI in the patients with early ACS. While the high analytical sensitivity increases clinical sensitivity for the diagnosis of myocardial infarction (MI), it is associated with decreased specificity and increased false positivity rates. The aim of this study was to evaluate the diagnostic value of Ultra-TnIin patients admitted to emergency department with chest pain and underwent coronary angiography. Methods: TnI levels of 200 patients who were admitted to the emergency department with chest pain and underwent coronary angiography were investigated retrospectively using hospital information system. Serum TnI levels were determined with Ultra-TnI reagent (Siemens Healthcare Diagnostic). The diagnostic performance of TnI was evaluated at first admission and within 12 hours. Results: False positivity and negative rates were determined as 26% and 32% at the first 3 hours. The sensitivity and specificity of TnI were 74% and 68% for the first 3 hours, respectively . With successive measurements, false negativity rate dropped to 9.6%, the sensitivity, the negative predictive value and the positive predictive value increased to 90%, 67% and 91%, respectively. Conclusion: Using a higher cut-off value,can cause difficulties in diagnosis of patients with early MI. Since troponin results above the accepted threshold value can also be due to reasons other than MI, increases or decreases between the series of measurements of troponin can be used to strengthen the idea of acute myocardial damage. For TnI, the more comprehensive prospective studies should be planned with detailed patient information to determine the lower cut-off value which ensures higher sensitivity, specificity, but lower false positivity and negativity rates.