Meningiomas are the most frequently reported central nervous system (CNS) tumors, accounting for 37% of all CNS tumors. Atypical meningiomas (WHO grade-II) show increased cellular proliferation and recurrence. Currently, no chemotherapy is part of the standard of care for meningiomas, and surgery followed by radiotherapy is the mainstay of treatment. Metabolism is the key to many biological processes including tumorigenesis. Unravelling metabolic phenotypes of various histological subtypes of meningiomas will identify new targets for the therapeutic intervention of these tumors. Here, we investigate the in vivo metabolism of [U-13C]glucose and [1,2-13C]acetate in meningioma patients using 13C NMR based isotopomer analysis.