Background: The aim of the present study was to evaluate the diagnostic accuracy of high-sensitivity troponin T (hsTnT) in patients with suspected acute coronary syndrome (ACS) in comparison to heart fatty acid-binding protein (H-FABP), high-sensitivity C-reactive protein, myeloperoxidase (MPO), and pentraxin 3 (PTX3). Methods and Results: Patients (n=432) with chest pain were recruited for the analysis. ACS was diagnosed in 298 patients (69%). The diagnostic accuracy of measurements obtained at presentation, as quantified by the area under the receiver operating curve (AUC), was highest for hsTnT (AUC=0.82; 95% confidence interval [CI]: 0.78-0.87) and H-FABP (AUC=0.83; 95%CI: 0.78-0.87). Sensitivity (87.9%) and negative likelihood (LH; 0.2) for hsTnT were the highest and lowest, respectively, but H-FABP had the highest specificity (78.5%) and positive LH (3.6). Among patients who presented within 2h after the onset of chest pain, MPO had the highest AUC (0.82; 95%CI: 0.69-0.94). Combined use of H-FABP and MPO measurements yielded a sensitivity of 69.2%, specificity of 84.2%, positive LH of 4.4, and negative LH of 0.4. Conclusions: The hsTnT assay offers excellent diagnostic performance to rule out ACS, but it is prone to false-positive results. H-FABP offers similar overall diagnostic performance, while the combination of H-FABP and MPO assays may improve the diagnosis of ACS, particularly in patients with recent onset of chest pain. (Circ J 2011; 75: 2813-2820)