Aim: To investigate the clinical implications of serum heart-type fatty acid-binding protein (H-FABP) compared to myoglobin, cardiac troponin I (cTnI), and creatine kinase MB isoenzyme (CK-MB) in patients with early phase acute myocardial infarction (AMI). Material and Methods: Patients were grouped clinically according to the American College of Cardiology/European Society of Cardiology new definition of myocardial infarction (MI) and by clinician diagnosis of MI. Serum concentrations of H-FABP, myoglobin, cTnI, and CK-MB were determined in 21 patients with AMI and 44 non-AMI patients. From each patient 3 blood samples were obtained 1-2, 3, and 6 h after the onset chest pain. The samples were compared to those of 20 age-matched healthy subjects. All the patients and healthy subjects had normal renal function. Results: At 1-2, 3, and 6 h after the onset of AMI, similar to myoglobin, the diagnostic sensitivity and specificity of H-FABP were higher than those of cTnI and CK-MB. Greater receiver operating characteristic (ROC) curve areas for the diagnosis of MI, by both sets of criteria, were obtained for H-FABP and myoglobin compared to both cTnI and CK-MB. Conclusion: H-FABP and myoglobin are reliable biochemical markers for superacute phase AMI and the changes in their serum concentrations have clinical significance in the diagnosis of AMI. ©copy; TüBİTAK.