Background and Objectives A large number of clinical studies have well demonstrated that the loss-of-function variant allele CYP2C19*2 is associated with attenuated response to clopidogrel and increased risk for developing stent thrombosis (ST) in white or black patients with stenting.However,similar association studies about effect of the CYP2C19*2 and *3 variants on maximum platelet aggregation (MPA) and the risk of cardiovascular events are currently unavailable for the Chinese patients.This work aimed to assess the impact of the CYP2C19 *2 and *3 variants on the antiplatelet effects and adverse cardiovascular events in clopidogrel-treated Chinese patients undergoing percutaneous coronary intervention (PCI).