Abstract: Objective:To investigate the significance of the detection of CYP2C19 gene polymorphism in guiding the treatment of acute cerebral infarction(ACI),and its correlation with the progress of ACI.Methods:The disease history,physical examination,routine admission test and CYP2C19 gene detection in 206 ACI patients were analyzed,and the patients were divided into the progressive cerebral infarction group and non-progressive group according to clinical symptoms.The fast metabolism,intermediate metablism and slow metabolism in the detection of CYP2C19 gene were further analyzed,and the effects of which on the clinical outcome of ACI patients treated with conventional method combined with antiplatelet was statistically analyzed.Results:The difference of the metablism type distribution of CYP2C19 gene between two groups was statistically significant(P<0.01),and the ratios of PM and EM genotypes in progressive cerebral infarction group were higher and lower than those in non-progressive group,respectively.Conclusions:The CYP2C19 gene polymorphism may be related to the disease progress in ischemic stroke patients treated with clopidogrel.