Abstract: Clopidogrel is a classic antiplatelet drug for acute coronary syndrome, but clinical observation shows that some patients do not benefit from clopidogrel therapy, and the issue of clopidogrel resistance (CR) is increased. CR is related to many possible factors and CYP2C19 polymorphism is one of the most important factors. Patients with genetic variants in CYP2C19 have been found to have lower levels of the active metabolites, less antiplatelet effect and a higher rate of major adverse cardiovascular events. Moreover, CYP2C19*2 and CYP2C19*3 are more common in Asian populations. Thus, study of the effect of CYP2C19 polymorphism on clopidogrel therapy is of clinical significance.