Objective To evaluate the significance of platelet function monitoring in anti-platelet treatment of acute myocardial infarction.Methods The platelet maximum aggregation rates(MAR) induced by arachidonic acid,adenosine diphosphate and collagen were detected in60 cases of acute myocardial infarction.The platelet aggregation function was compared before and after anti-platelet therapy for 24 h and 1week.The plasma concentration of clopidogrel acid was detected and the correlation between concentration of clopidogrel acid and platelet aggregation was analyzed.Results The MAR induced by arachidonic acid,adenosine diphosphate and collagen were significantly decreased after antiplatelet treatment for 24 h(P 0.01); but after 1 week,no further reduce in platelet aggregation rate was found,which showed some tolerance.After 24 h,patients with MAR decreased by more than 30% accounted for 36.5%,40.4% and 21.2%,respectively induced by arachidonic acid,adenosine diphosphate and collagen; patients with MAR decreased by 10%-29% accounted for 30.8%,25%,and34.6%,respectively,and those with MAR decreased less than 10% accounted for 34.6%,36.5% and 44.2%,respectively.During half year follow-up,34% of patients showed reoccurrence of cardiovascular events,and 55% of them were found aggregation rate less than 30%.Conclusion The aggregation rates under induction of arachidonic acid,adenosine diphosphate and collagen are all less than 30% when adopting the same anti-palate regime,but the incidence of cardiovascular events increased significantly and the platelet aggregation function and blood concentration of clopidogrel acid has no correlation.