【Objective】To investigate the relationship between clopidogrel response，early neurological deterioration and CYP2C19 gene polymorphism in sICAS patients.【Methods】116 sICAS patients were divided into deterioration group and non-deterio? ration group by whether appear early nervous function deterioration. Record included the baseline data，the genotypes of CYP2C19， platelet maximum aggregation rate after 7 days of given clopidogrel，CYP2C19 genotype and clopidogrel reaction were compared be? tween two groups.【Results】The deterioration group combination with diabetes，stroke/TIA were significantly higher than the non-de? terioration group（P<0.05）；The frequency of CYP2C19*2 AA genotype and A allele were significantly higher than those in non-dete? rioration group. The frequency of GG genotype were significantly lower than non-deterioration group（27.27% vs 2.13%，50.00% vs 14.84%，27.27% vs 72.34%）（P<0.01）；The poor metabolic genotype platelet maximum aggregation rate were significantly higher than that of the fast-metabolic genotype and middle metabolic genotype（P<0.01，P<0.05），Middle metabolic genotype platelet maxi? mum aggregation rate were significantly higher than fast-metabolic genotype（P<0.01）；The deterioration group fast-metabolic geno? type were significantly lower than non-deterioration group，poor metabolic genotype were significantly higher than non-deteriorationgroup（22.73% vs 65.96%，36.36% vs 5.32%）（P<0.01）；Clopidogrel resistance rate 59.09% were significantly higher non-deteriora? tion group 28.72%（P<0.05）. 【Conclusion】Clopidogrel response and early neurological deterioration in sICAS patients is associated with CYP2C19 gene polymorphism.