Objective To observe and analyze the difference of CYP2C19 gene polymorphism and serum valproic acid concentration in the patients with epilepsy to provide reference for clinical individualized medica-tion .Methods A total of 148 patients with epilepsy in the hospital from January 2015 to December 2016 were selected and their CYP2C19 genotypes were detected by adopting the real-time fluorescence polymerase chain reaction ,meanwhile the cases were given the valproic acid treatment .Then the correlation between CYP2C19 gene polymorphism and serum valproic acid concentration was analyzed .Results There was great individual differences in serum valproic acid concentration difference among CYP2C19 genotypes ,in which the alleles and genotypes distribution frequency had no statistically significant difference among 148 cases of epilepsy ( P>0 .05);Serum valproic acid concentrations at 2 ,4 ,8 h after medication in the patients with AA genotype at CYP2C192 locus were significantly higher than those in the patients with GG genotype at CYP2C192 lo-cus ,the difference was statistically significant (P<0 .05);Serum valproic acid concentrations at 8 h after medi-cation in the patients with AA genotype at CYP2C193 was significantly higher than that in the patients with GG genotype at CYP2C193 locus ,the difference was statistically significant (P<0 .05);Serum valproic acid concentration had no statistically significant difference among other genotypes (P> 0 .05) .Conclusion The CYP2C19 gene in the patients with epilepsy has polymorphism ,moreover which is correlated with the patient′s blood concentration of vaproic acid .Therefore ,treating the patients with epilepsy by using valproic acid can detect the CYP2C19 genotyping in the patients in order to guide their individualized treatment .