This work discusses intranasal delivery ofperillyl alcohol (POH) as a potential adjuvant therapeutic strategy for patients with relapsing malignant gliomas.POH is a monoterpene with preclinical antitumor activity in several types of tumor in rodent models and is currently under phase Ⅰ and phase Ⅱ clinical trials.The proposed mechanism of action involves inhibition of post-translational isoprenylation of small G proteins, including p21-Ras, thereby blocking signal transduction.Deregulated p21-Ras function, as a result of mutation, overexpression or growth factor-induced overactivation, contributes to growth of malignant gliomas.Intranasal delivery is a practical and non-invasive approach that allows therapeutic agents which do not cross the blood-brain barrier (BBB) to enter the Central Nervous System (CNS), reducing unwanted systemic side effects.Applying this method we performed a phase Ⅰ / Ⅱ study of POH in patients with relapsed malignant gliomas after standard treatment: surgery, radiotherapy and chemotherapy.