The treatment of cerebral gliomas continues to challenge neurosurgeons and research scientists. The lack of major success with chemotherapy and radiation therapy has given rise to further investigation into the biology of these tumors and host reactions to them. Much of this research has centered upon the evaluation of tumor cell antigenicity and on both the humoral and cellular immune responses to gliomas. Contrary to previous considerations, evidence suggests that astrocytes, glioma cells, and tumor endothelial cells may all have pivotal roles in the initiation and prolongation of both local and systemic immune responses to the tumor. In this review we will discuss the immunobiology of the glioma with specific reference to the interactions between the tumor and the host immune system. In addition, ideas for potential therapeutic manipulation of the host-glioma immune interactions will be reviewed, stressing potential pitfalls and risks.