Abstract: AIM:To assess the risk factors of low clopidogrel responsiveness in patients with coronary heart disease (CHD) and analyze the relationship between low clopidogrel responsiveness and recurrent cardiovascular events after PCI. METHODS: A total of 400 patients with CHD were assigned to clopidogrel low responder group (n=79) and responder group (n=321) according to the results of ADP (10 μmol/L)-induced platelet aggregation. All patients received a conventional dose of clopidogrel for 3 days or more or oral 300 mg loading dose of clopidogrel for at least 6 h. Possible risk factors of low clopidogrel responsiveness were analyzed by single factor analysis and multifactor gradual logistic regression analysis. All patients were followed for 9 months after PCI and the primary endpoint was perioperative myocardial infarction, stent thrombosis, acute myocardial infarction, cardiac death and stroke. RESULTS: The incidence of low clopidogrel responsiveness was 19.8%. Platelet aggregation rates were (49±9) and (18±11), respectively, in the two groups (P<0.01). Multivariate logistic regression analysis found that low clopidogrel responsiveness was positively correlated with diabetes mellitus (OR 1.954, 95%CI 1.036-3.683, P<0.05), hyperlipidemia (OR 1.915, 95%CI 1.014-3.617, P<0.05) and plasma fibrinogen (OR 1.431, 95%CI 1.089-1.882, P<0.05). Cardiovascular events occurred in 16 patients (20%) in the low clopidogrel responsiveness group and 37 patients (12%) in the control group. CONCLUSION: Diabetes mellitus, hyperlipidemia, plasma fibrinogen and the history of prior PCI are the influencing factors of low clopidogrel responsiveness. Low clopidogrel responsiveness increases the incidence of recurrent cardiovascular events.