Molecular and clinical observations suggest a role of sex steroid hormones in the occurrence of meningioma. However, there is limited and often conflicting data on the use of hormone replacement therapy (HRT) as a possible risk factor for meningioma. The goal of this study was to investigate whether there is an association between a diagnosis of meningioma and either current or past HRT use in women. We retrospectively reviewed records in the Mayo Clinic Jacksonville electronic patient database between 1993 and 2003 to identify women with a diagnosis of either symptomatic or incidentally discovered, clinically silent meningioma. Records were also searched to identify women with a documented history of either current or past HRT use. Of the 355,318 women, ages 26 to 86, evaluated for any medical issue, 18,037 (5%) were documented as current or past HRT users. A total of 1,390 women with a history of symptomatic or incidentally discovered meningiomas were identified, 156 (11%) of whom were either current or past HRT users. A logistic regression analysis, adjusted for age, demonstrated a positive association between a diagnosis of meningioma and HRT use, with an odds ratio of 2.2 (95% CI, 1.9 to 2.6; P < .0001). The frequency of meningioma in women with either current or past HRT use was 865 in 100,000, whereas the frequency of meningioma in women without the history of HRT use was 366 in 100,000. The study provides evidence of a positive association between HRT use and diagnosis of meningioma, and therefore, HRT use may be a risk factor for meningioma.