Aldosterone participates in vascular and myocardial inflammation either directly or indirectly through blood pressure (BP). Aldosterone synthase (CYP11B2) C-344T polymorphism may influence the severity of systemic inflammation. A total of 398 Japanese Americans (152 men and 246 women, age 19-92 years) from the Hawaii-Los Angeles-Hiroshima study were enrolled. BP and serum levels of C-reactive protein (CRP) were measured, and the CYP11B2 C-344T polymorphism, rs1799998, was determined. No influence of the polymorphism on baseline characteristics such as systolic, diastolic and mean BP, pulse pressure or serum CRP levels was observed. In all genotypes, systolic BP showed a significantly positive correlation with age (TT (n=178): r=0.283, P<0.001; TC (n=164): r=0.213, P=0.006; and CC (n=56): r=0.289, P=0.031). However, the regression coefficients of systolic BP with age were not different across genotypes. According to the results of univariate and multivariate analyses with adjustment for BP, the serum CRP level increased with age only in subjects with the CC genotype (P=0.027 and P=0.004, respectively), and elevation of serum CRP was mainly observed in the elderly population (aged >or=60 years). Moreover, the regression coefficient of CRP levels with age was significantly steeper in subjects with the CC genotype than in those with the TC or TT genotype (P=0.028). The CC genotype of the CYP11B2 C-344T polymorphism was associated with an age-dependent increase in the serum CRP level independent of BP, and may contribute to a cardiovascular phenotype by promoting vascular inflammation.