Objective To investigate the influence of aspirin and/or clopidogrel treatment on platelet aggregation rate in coronary heart disease (CHD) patients,and discuss the factors related to anti-platelet drug resistance.Methods A total of 160 patients with CHD and received aspirin and/or clopidogrel treatment were enrolled in the Second Xiangya Hospital,Central South University,and were divided into stable coronary heart disease (SCHD) group (n =90) and acute coronary syndrome (ACS) group (n =70).Meanwhile,non-coronary heart disease (NCHD) patients who did not receive anti-platelet drug treatment were enrolled as controls (n =50).Clinical data of the subjects were recorded.The maximum platelet aggregation rate induced by arachidonic acid (MAR-AA) and adenosine diphosphate (MAR-ADP) were evaluated with sequential platelet counting method.The factors related to drug resistance were analyzed with Logistic regression analysis.Results Compared to NCHD group,there were lower MAR-AA and MAR-ADP in two groups of CHD (all P ＜ 0.05).In ACS patients,MAR-AA and MAR-ADP are significantly lower (P ＜0.05) in patients who receive the aspirin and clopidogrel.The rate of anti-platelet drug resistance in ACS group was significantly higher than that in SCHD group (20.0％ vs 10.0％,P ＜ 0.05).Multivariate logistic regression analysis showed that low HDL-C (＜ 1.0 mmol/L) was an independent risk factor related to the anti-platelet drug resistance (OR =4.36,95 ％ CI:1.36-14.02,P =0.025).Conclusions The antiplatelet treatment with aspirin and/or clopidogrel can significantly reduce the platelet reactivity in CHD patients,but some patients still present anti-platelet drug resistance.The combination of aspirin and clopidogrel is better.The rate of drug resistance in ACS patients is high.Low HDL-C might be associated with anti-platelet drug resistance.