Abstract: Objective: To evaluate the diagnostic efficacy and value of heart-type fatty acid-binding protein(H-FABP) in the super early hours of acute myocardial infarction(AMI).Methods: Seventy-five patients hospitalized within 12 hours after onset of chest pain and determined as AMI were enrolled in the study group.Among them,29 patients were sent to hospital within 4 hours of onset and others within 4 to 12 h.Twenty-five healthy peoples with normal coronary angiogram(CAG) were enrolled in the control group.The AH-FABP and troponins I(cTnI) concentrations of the two groups were measured by sandwich ELISA,and the receiver operating characteristics(ROC) curves for diagnosing AMI within 4 h and within 4-12 h were then generated and compared.The areas under the curve(AUC) were calculated.The sensitivity,specificity,Youden index,NPV and PPV were calculated and compared by using the Pearson Chi-squared test.Results: The AUC,sensitivity,Youden index and NPV of H-FABP within 4 hours were much higher than that of cTnI(P<0.01);and the AUC,sensitivity,Youden index and NPV revealed no significant difference within 4-12 h(P>0.05).Conclusions: H-FABP is effective for early diagnosis of AMI.Within 4 to 12 hours after onset of chest pain,it is as good a marker as cTnI.But within 4 hours,it has a much higher AUC and NPV than cTnI.It is very useful for confirmation or exclusion of AMI in the early stage.