Objective To explore the effect of CYP2C19 gene polymorphism on occurrence of adverse events in elderly patients receiving vertebrobasilar stenting. Methods A retrospective analysis was made of the clinical data of 108 patients aged over 60 years who were hospitalized for ischemic stroke and underwent vertebral artery stenting in Clinical College of First Center, Tianjin Medical University between February 2013 and March 2017. Patients were divided into mutant group (46 cases) and wild-type group (62 cases) according to genotype. The platelet inhibition rate and adverse events in two groups were observed. SPSS statistics 19.0 was used for statistical analysis. Depending on the data type, t-test or χ² test was used for comparison between groups. Multivariate binary logistic regression was performed to analyze factors associated with recurrence of ischemic stroke. Results The platelet inhibition rate in mutant group was (54.3±5.6)%, while in wild-type group was (69.7±3.8)%, and the difference was statistically significant (P＜0.001). The incidence of bleeding was 2.2% (1/46) in mutant group and 4.8% (3/62) in wild-type group, with no significant difference between two groups(P＞0.05). The incidence of recurrent cerebral infarction was 32.6% (15/46) in mutant group and 4.8% (3/62) in wild-type group, and the difference was statistically significant (P<0.001). The recurrence rate of in-stent restenosis of vertebral artery was higher in the mutant group [43.5% (20/46)] than that of wild-type group [11.3% (7/62)], and the difference was statistically significant (P<0.001) . Conclusion Elderly patients with mutant CYP2C19 have a higher risk than wild-type patients for restenosis and recurrent ischemic stroke after vertebral artery stenting. Detection of CYP2C19 genetic polymorphism helps reduce incidence of ischemic cerebrovascular events.