Abstract: Objective: To investigate the correlation between CYP2C19 gene polymorphism and platelet aggregation function. Methods: A total of 143 patients with cerebral infarction were selected as the study subjects.Fasting blood samples were collected with 3.8% sodium citrate anticoagulation to detect platelet aggregation function induced by adenosine diphosphate (ADP),expressed as the maximum platelet aggregation rate (MAR).Simultaneously,EDTA-K₂ anticoagulated blood was collected,and the CYP2C19 gene polymorphism was detected using fluorescent quantitative PCR.Differences in platelet aggregation function among patients with different CYP2C19 gene metabolizer types were analyzed.According to the MAR,the 143 subjects were divided into clopidogrel-resistant group and clopidogrel-nonresistant group,and differences in CYP2C19 gene polymorphism between the two groups were analyzed and compared.Multivariate logistic regression analysis was used to identify independent risk factors for clopidogrel resistance. Results: The MAR of patients with the CYP2C19 slow metabolizer type was significantly higher than those with the intermediate and fast metabolizer types,with statistically significant differences among the three metabolizer types (P<0.01).The proportion of the *1/*1 genotype in the clopidogrel-nonresistant group was 48.28%,which was higher than those in the resistant group (7.41%) (P<0.01).The proportions of the *2/*2 and *2/*3 genotypes in the clopidogrel-nonresistant group were both 1.72%,which were lower than those in the resistant group (40.74% and 14.81%,respectively) (P<0.01).Multivariate logistic regression analysis revealed that the CYP2C192 genotype was an the independent risk factor for clopidogrel resistance(B=2.112,P<0.01). Conclusions: Platelet aggregation function in patients with cerebral infarction is related with CYP2C19 gene polymorphism.The MAR (ADP-induced) has essential value for predicting clopidogrel resistance,which provides an important theoretical basis for individualized clinical medication and treatment.