Sex-based differences in the rates of primary brain tumor exist regardless of age or geographical location. Reports from around the world describing the incidence of common brain tumors as a function of sex are identified and linked to their countries of origin. Numbers shown in the parentheses are the sex ratio (male/female) of major primary brain tumor types extracted from 16 independent publications from 15 countries, including all major continents and regions of the world (North America, South America, Europe, Middle East, Africa, Asia and Oceania) except for Antarctica. Overall, these studies covered the period of 1974 to 2008, and the sex ratio (male/female) in almost all major brain tumors including both malignant and benign tumors is greater than 1 with a range of 1 to approximately 3.5. See also [2, 10–24]. Abbreviations: AST = astrocytoma; EPD = ependymoma; GBM = glioblastoma (multiforme); Glioma, (NOS) = glioma, not otherwise specified; MB = medulloblastoma; OLG = oligodendroglioma; PA = pilocytic astrocytoma.