Temozolomide has demonstrated clinical antitumor efficacy against malignant gliomas at both relapse and initial diagnosis. This drug appears to have less adverse effects compared to other drugs used against brain tumors. Therefore, temozolomide is often better tolerated in brain tumor patients compared to other brain tumor drugs. The current study builds on previous research to test the efficacy of chemotherapy alone in patients with anaplastic oligodendroglioma and mixed oligoastrocytoma.