The objective of this study was to investigate the association of polymorphisms in the aldosterone synthase gene CYP11B2 (-344T/C, Lys173/Arg, and an intronic conversion [IC]) with stage-2 hypertension in northern Han Chinese. A total of 503 hypertensives and their age-, gender-, and area-matched controls were included in this study. The female hypertensives had significantly higher frequencies of the -344T, 173Lys, and IC-conversion alleles (p = 0.002, 0.002, and 0.014, respectively). The estimated frequency of haplotype composed of the -344T, 173Lys, and IC-conversion alleles (haplotype 4) was significantly higher in the female hypertensives compared with their controls (p = 0.007). Using a multivariate score test, we found that haplotype 4 remained associated with female hypertension after the adjustment for covariates (p = 0.003), while the haplotype 3 of T-Arg-WT showed a protective effect both in the males and in the females (p = 0.03 and 0.006, respectively). The odds ratio for haplotype phase of 4-4 was 2.60 (95% CI, 1.21-5.58) and for 3-3, 0.20 (95% CI, 0.03-0.77). These results indicate that the Lys173 and the IC-conversion allele of the CYP11B2 gene confer an increased risk for stage-2 hypertension in northern Han Chinese women.