Intracranial meningiomas arise from the meninges and typically have benign histologic findings. They constitute approximately 20% of all intracranial tumors. Their incidence increases with age, and they affect women more commonly than men. The annual incidence per 100,000 people ranges from two to seven for women and from one to five for men. Since the first study was published in 1970, only eight major epidemiologic studies have been done that attempted to identify risk factors for meningioma. Ionizing radiation and head trauma have emerged as the most promising etiologic risk factors. In these studies, radiation doses as low as 1-2 Gy have been associated with increased risk. The role of dental radiographs has been suggested in some studies but not supported in others. An explanation for the apparent excess of meningiomas in women remains obscure. The potential effects of endogenous or exogenous sex hormones on tumor induction or growth remain unexplored in epidemiologic studies. More should be learned about the risk factors for meningioma in search of opportunities for prevention.