In this study, we found that the frequency of the genotype C602A was significantly different between hypertensive patients and healthy normotensive subjects (P = 0.005). Moreover, the prevalence of the A allele was markedly higher in hypertensive patients than in healthy subjects (OR = 0.42, P = 0.001). Because a significant association of the SNP C602A with essential hypertension was obtained in a multivariate analysis after adjusting for confounding risk factors, including age, body weight and height, the A allele of C602A may be an independent risk factor for hypertension. Grouping the subjects in this study by sex revealed that males exhibited a similar association with essential hypertension, whereas females did not, possibly indicating that C602A is more significantly associated with hypertension in males. On the basis of these results, we conclude that C602A is associated with hypertension. The frequency of the T1559C SNP was also significantly different between normotensive subjects and hypertensive patients when grouped by sex. A multivariate analysis, applied as described above, also indicated an association between T1559C and hypertension.