Immunotherapy is a potential new therapeutic option in patients with high-grade gliomas (HGGs). Phase I/II trials have assessed the efficacy of increasing immune activity using vaccines made from lymphokine-activated killer cells, cytotoxic T cells, autologous tumor cells, or dendritic cells. Studies to decrease tumor immunoresistance have focused on cytokine modulation of known immunosuppressive factors in the tumor microenvironment. Several early studies have reported a survival benefit using different forms of immunotherapy. This article discusses past clinical trials using immunotherapy in HGGs, their efficacy, limits, and biologic and clinical design challenges that must be overcome to advance immunotherapy for patients with HGGs.