As the presence of the p.R132H mutation in the IDH1 gene seems to be a more powerful prognostic marker than O(6)-methylguanine-DNA methyltransferase promoter status, we evaluated the presence of IDH1 mutation in Polish patients with astrocytoma, glioblastoma, oligoastrocytoma, ganglioglioma, oligodendroglioma, and ependymoma.