Abstract: Objective　To investigate the Pselectin expression on platelet surface and the correlation between platelet Pselectin and platelet aggregation function before percutaneous coronary intervention (PCI).   Methods　A total of 51 patients with coronary heart disease undergoing PCI， including 9 cases of ST segment elevation acute coronary syndrome (STE ACS)， 36 cases of nonST segment elevation acute coronary syndrome (NSTE ACS) and 6 cases of stable angina(SA), and 14 healthy subjects were as controls. Platelet Pselectin and platelet aggregation function were determined by whole blood flow cytometric assay and light transmittance aggregometry，respectively.  Results　There were significant differences in the platelet Pselectin among all groups（F=16.915，P=0.001）. STE ACS patients had significantly elevated levels of platelet Pselectin comparing with the other groups(P<0.05). There was no statistical significance among NSTE ACS, SA and control groups. No significant correlation was identified between the platelet Pselectin and adenosine diphosphate and arachidonic acidinduced maximal platelet aggregation (r=0.038，P>0.05; r=0.165，P>  0.05). Conclusions　The elevated platelet Pselectin expression is likely correlated with STE ACS. Combining with platelet aggregation test， the detection of platelet Pselectin may be a valid tool to assess posttreatment platelet activity. 

Key words: P-selectin, Platelet function, Percutaneous coronary intervention