Experimental evidence indicates that angiotensin-converting enzyme 2 (ACE2), a homologue of human ACE, might negatively regulate the activated renin-angiotensin-aldosterone system (RAAS) and might function as a protective regulator in the pathogenesis of hypertension. However, association studies regarding ACE2 are sparse in the literature, with negative results in the majority of cases. Here we conducted an association study between 2 intronic polymorphisms (A1075G and G8790A) of the ACE2 gene and stage 2 hypertension in Han Chinese. We genotyped the 2 polymorphisms in 1494 subjects (808 stage 2 hypertensives and 686 normotensives) recruited from the Fangshan district (Beijing). Data were analyzed using chi(2) test, 1-way analysis of variance, and logistic regression where appropriate. The frequency of A1075G allele distribution in males differed significantly (P < 0.0001), whereas the genotype and allele distributions of G8790A polymorphism were similar, between stage 2 hypertensives and normotensives. Systolic blood pressure (SBP) differed significantly in females across both genotypes: SBP was significantly lower in subjects with the 1075AA and 8790GG genotypes, higher in the 1075GG (+13.65 mm Hg versus AA) and 8790AA (+13.36 mm Hg versus GG) genotypes, and intermediate in the 1075AG (+5.76 mm Hg versus AA) and 8790GA (+5.65 mm Hg versus GG) genotypes. Our data suggest that the polymorphism (A1075G) might be a risk factor-at least a marker-for stage 2 hypertension in males and that the 2 studied polymorphisms might be the indicators of systolic hypertension in females.