This chapter outlines the current clinical application of interferon for treatment of brain tumor, especially glioma. Since approved as a therapeutic drug for brain tumor originally produced in Japan, interferon-beta has been reported to be effective when it was used alone, in combination with chemo-radiotherapy (ACNU/MCNU as a nitrosourea derivative chemodrug, and radiation for 60 Gy totally). Recently, the regimen of combination with interferon-beta have been improved to obtain a higher efficacy rate. For example, as a fundamental study, temozolomide is an enthusiastic chemodrug to enhance the anti-tumor effect of interferon-beta when it is combined, pre-clinical and clinical trial will be scheduled. As for interferon-beta gene therapy by means of liposome as ad drug delivery system, already clinical trial has been performed and clinical safety and effectiveness have been proved, and it is expected that newly development in the field of gene therapy will be established and improvement of therapeutic results for malignant brain tumor will be achieved.