The gene encoding RhoA guanine nucleotide exchange factor 10(ARHGEF10) has been reported to be a risk factor for atherothrombotic stroke (AS) in Japanese. The single-nucleotide polymorphism (SNP) rs4376531 in intron 16 on ARHGEF10 is associated with AS and may play a role in the disease pathology. In order to explore the nature of this association in greater detail and in a new ethnic group, we carried out a case-control study to determine whether the rs4376531 polymorphism in ARHGEF10 is a risk factor of AS in Han Chinese people. This study was carried out to assay the frequency of genotypes and alleles of SNP rs4376531 in ARHGEF10 in patients with ischemic stroke and healthy controls using the polymerase chain reaction and the restriction fragment length polymorphism (PCR-RFLP) technique. A total of 383 individuals with AS in West China Hospital and 214 unrelated healthy controls were recruited. The frequencies of the G allele and GG genotype of the rs4376531 polymorphism were higher in the patients with AS than in control individuals: frequency of G, 91.0% vs 83.4%, P<0.001; GG, 82.2% vs 67.8%, P<0.001. After adjusting for sex, age, and multiple cardiovascular risk factors, the homozygous GG genotype for this variant was associated with a higher risk of AS, with an adjusted odds ratio of 4.99 (95% CI, 2.55-7.81, P< 0.001). Our findings suggest that the rs4376531 polymorphism in the ARHGEF10 gene is a risk factor for AS in the Han Chinese population.