Several genetic polymorphisms in endothelial nitric oxide synthase (eNOS) are associated with the pathogenesis of rheumatoid arthritis (RA). This study explored the effect of eNOS gene polymorphism on genetic susceptibility of RA in Chinese Han population. Patients with RA (n=236) and healthy volunteers (n=240) were enrolled in this study. Genotyping of eNOS T-786C and G894T polymorphisms was performed by polymerase chain reaction-restriction fragment length polymorphism. Genotyping and gene frequency distribution of eNOS T-786C and G894T polymorphisms were evaluated. RA patients showed higher frequencies of mutated TC and CC genotypes of eNOS T-786C polymorphism and mutated GT and TT genotypes of G894T polymorphism than healthy controls. More specifically, the genotype frequencies of eNOS T-786C polymorphism were significantly different between RA patients and controls. The expression of eNOS was enhanced in RA patients compared with controls. Further, eNOS expression was enhanced after C was replaced with T in T-786C polymorphism in the promoter. Overall, the individuals with mutations in T-786C and G894T of eNOS may have an increased risk of RA, and T-786C and G894T polymorphisms of eNOS are associated with genetic susceptibility of RA in Chinese Han population.