The present invention provides a number of gene markers whose expression is altered in various gliomas. In particular, by examining the expression these markers, one can accurately classify a glioma as glioblastoma multiforme (GM), anaplastic astrocytoma (AA), anaplastic oligodendroglioma (AO) or oligodendroglioma (OL). The diagnosis may be performed on nucleic acids, for example, using a DNA microarray, or on protein, for example, using immunologic means. Also disclosed are methods of therapy.