Aim To investigate TFPI V264M polymorphism in Chinese and its effect on plasma levels of free tissue factor pathway inhibitor(f-TFPI) and severity of acute coronary syndrome(ACS). Methods The genotypes of V264M were detected by PCR and PCR-RFLP in 136 ACS patients and 106 controls undergoing coronary angiography,then the serum f-TFPI level in 57 cases was inspected by enzyme linked immunosorbent assay. Results The allele and genotype frequencies were consistent with that predicted by Hardy weinberg equilibrium in the present study population(χ~2=0.437,p<0.05).Plasma f-TFPI level was significantly lower among carriers of Aallel as compared with non-carriers(GG genotype)[6.9±5.1) vs(14.3±9.5)].ACS group showed significantly higher plasma level of f-TFPI than control group(p<0.05).No meaningful corelationship was found between ACS group and control group for V264M polmorphism(p<0.05). Conclusion The V264M polymorphism do have an effect on the serume f-TFPI level but have no relationship with the occurrence and the severity of ACS.