Objective: To observe the changes of heart-type fatty acid binding-protein(H-FABP) in the femoral vein(periphe ral blood) and urine of rats with myocardial infarction in different postmortem intervals. Methods: Acute myocardial infarction (AMI) was duplicated by ligating the anterior branch of the left coronary artery following the method of Johns in rats. Concentrations of H-FABP were detected with enzyme-linked immuno-sorbent assay (ELISA). Results: The concentrations of H-FABP in experiment group were obviously higher than that in control group. Along with the time, the concentrations of H-FABP in experiment group rose consistently, the concentration of H-FABP in 12 h group rose markedly, and it was obviously higher than in 48h that in 24h. The H-FABP concentrations in urine of the experiment group were obviouslyhigher than the one in control group. The urine concentrations of H-FABP in experiment group increased by wavy in postmortem intervals, the concentration of H-FABP in (6h) group was obviouslyhigher than that in 0h group, 12h and 24h postmortem, the H-FABP concentrations decreased, but still higher than that of 0h group and 48h group, the concentration of H-FABP rose markedly and washigher than 6h group. Conclusion: Affected by autolysis, the H-FABP concentrations of plasma and urine appeared abnormal raise and can not be used in postmortem diagnosis of AMI.