The majority of primary CNS tumors in adults are comprised of neuroepitelial tumors (gliomas).The diagnosis has historically been based upon the histologic appearance of these tumors.However, as molecular data has accumulated, there is considerable evidence that the molecular diversity (even within the same diagnostic entity) may account for the heterogeneity of clinical outcomes, such as response to treatment, time to progression and overall survival after diagnosis.These molecular markers are becoming more useful in the field of neuro-oneology.They can assist in diagnosis, provide prognostic information and potentially predict response to therapy.Perhaps, the greatest potential for these molecular aberrations is that they may represent therapeutic targets themselves.In this presentation, I will summarize the findings of important, published biomarker studies in adult glioma and provide an overview of the practical uses of these markers in the clinical setting, as well as the current understanding of molecular gliomagenesis.