The association between aldosterone synthase (CYP11B2) gene polymorphism and white matter hyperintensities seen on cerebral MRI was studied in a population-based sample of 829 individuals aged 63 to 75 years. The T allele was associated with the risk of severe white matter hyperintensities. Compared with the CC genotype, the adjusted OR for severe white matter hyperintensities was 4.61 (95% CI, 1.46 to 14.55) for the TT genotype and 2.45 (95% CI, 0.81 to 7.46) for the TC genotype in men. This association was independent of hypertension.