Extensive resection of malignant gliomas without compromising neuronal function has been believed to prolong the survival of the patients. Among the therapeutic triad, radiation therapy has been shown to improve overall survival. Recent publication of a positive phase 3 trial comparing radiation therapy (RT) alone with RT and temozolomide chemotherapy in patients with glioblastomas introduced a new standard chemotherapy. Significan atdvantage was detected of the patients who have methylated MGMT promoter in the treatment of temozolomide. On the other hand, oligodendrogliomas with 1p/19q loss was reported to have good clinical course without PCV chemotherapy T. heses examples show that genomic analyses such as 1p/19qd eletion or MGMT status in glial tumors are necessary to predict sensitivity against chemotherapy.