Objective:To explore relationship among expressions of CC type chemokine ligand 2 (CCL2) and its re-ceptor (CCR2) and platelet aggregation rate in patients with acute myocardial infarction (AMI).Methods:A total of 60 AMI patients treated in our coronary care unit were regarded as AMI group,another 60 healthy subjects un-dergoing physical examination were enrolled as normal control group.Plasma CCL2 level,expressions and location of platelet CCL2 and CCR2 in coronary thrombus tissue were measured in two groups.Changes of activated glyco-protein Ⅱb/Ⅲa compound (PAC-1) and CD62p levels,and influence of different CCL2 level on platelet aggregation rate (PAR) were compared in normal control group before and after CCL2 stimulus.Results:Compared with nor-mal control group,there were significant rise in plasma CCL2 level [ (159.63 ± 54.32) pg/ml vs.(218.79 ± 76.34) pg/ml],expressions of platelet CCL2 [ (0.86 ± 0.38) vs.(2.05 ± 0.59)] and CCR2 protein [ (0.93 ± 0.42) vs.(2.67 ± 0.51)] in AMI group (P＝0.001 all),co-location expression relationship existed between CCL 2/CCR2 and CD62p in AMI patients.Compared with before CCL2 stimulus,there were significant rise in expressions of PAC-1 [ (9.83 ± 3.14)% vs.(18.96 ± 4.25)%] and CD62p [ (5.08 ± 1.16)% vs.(8.33 ± 1.89)%] in normal control group after CCL2 stimulus,P＝0.001 both.When CCL2 ≥100ng/ml,maximum PAR was significantly higher than that of CCL2＝0ng/ml level,P＝0.001 all.Conclusion:Expression of CCL2/CCR2 is closely associated with plate-let aggregation rate in AMI patients.CCL2/CCR2 may be involved in disease progress via affecting platelet aggrega-tion rate.