Abstract: Objective To investigate the correlation between NAD (P)H oxidase p22phox C242T polymorphism and transient ischemic attack (TIA). Methods This study involved 138 Chinese patients with TIA and 130 control subjects, from whom genomic DNA was obtained to determine the p22phox C242T polymorphism using polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). Results The CT genotype frequencies in the TIA group and control group were 0.268 and 0.139, respectively, and no TT genotype was found. The CT genotype and T allele frequency of the TIA group was significant higher than that of the control group (p<0.05). Conclusion The NAD(P)H oxidase p22phox C242T polymorphism may serve as a risk factor for TIA.