OBJECTIVE: Glioblastoma multiforme (GBM) has a poor prognosis. The purpose of this systematic review and meta-analysis was to analyze the outcomes of clinical trials which compared immunotherapy with conventional therapy for the treatment of malignant gliomas. METHODS: PubMed, Cochrane and Google Scholar databases were searched for relevant studies. The 2-year survival rate was used to evaluate effectiveness of immunotherapy. RESULTS: Of 171 studies identified, six comparative trials were included in the systematic review. Immunotherapy was associated with a significantly longer OS and 2-year survival compared to conventional therapy. CONCLUSION: Immunotherapy may improve the survival of patients with GBM.