Abstract: The concurrent administration of chemotherapy and immunotherapy has been considered a contraindication because of the concern that the induced lymphopenia would ablate therapeutic efficacy of immunotherapy. Temozolomide has been shown to be an effective chemotherapeutic for patients with malignant gliomas and to deprive patients with glioblastoma (GBM) patients of this agent in order to treat with immunotherapy is controversial. Despite conventional dogma, we demonstrate that both chemotherapy and immunotherapy can be delivered concurrently without negating the effects of immunotherapy, in fact, the temozolomide induced lymphopenia may actually be synergistic with a peptide vaccine.