Abstract: Objective To investigate the association of 27 bp variable number of tandem repeat(VNTR)polymorphism of the endothelial nitric oxide synthase(eNOS)gene with essential hypertension(EH)in the Kazakh and Han population in Xinjiang. Methods A total of 363 Kazakh patients(case group)with EH,370 healthy Kazakh people(NT group)and 346 Han EH patients,385 healthy people in Han Chinese population were selected from Tacheng area in the Xijiang.27 bp VNTR polymorphism of eNOS gene was detected with multiplex snapshot system.Genotypic and allele frequency were calculated and compared.Blood samples were collected and the blood level of eNOS was quantified using sandwich enzymelinked immunosorbent assay. Results For the two different ethinc EH groups,the average levels of systolic blood pressure, diastolic blood pressure,average arterial pressure,body mass index,waist/hip ratio,cholesterol,low density lipoprotein,creatinine,uric acid,and apolipoprotein A1/B were all higher than those of the NT group(P<0.05 for all).The frequencies of genotype of 27 bpVNTR polymorphism of eNOS gene(bb,aa,ab,bc)had no difference between EH and NT groups in the Kazakhs(P>0.05).The frequencies of genotypes and alleles of eNOS gene had no difference between EH and NT groups in Han population(P>0.05),and the bc genotype was not detected in Han EH group.The average plasma eNOS levels were 12.31±15.63,13.25±13.55,and 14.27±18.94 ng/ml for Han EH patients with bb,aa,and ab genotype and those were 13.84±15.19,17.97±13.33,and 13.55±13.73 ng/ml for Han controls with bb,aa,and ab,respectively,and the levels of Han populations of different groups were all higher than those of Kazakh populations. Conclusion The polymorphism of 27 bpVNTR eNOS gene was not associated with essential hypertension in Kazakh and Han population of Xinjiang. The Han populations with bb,aa,and ab genotype have a higher average eNOS level than Kazakhs.