Gliomas are the most common primary intracranial brain tumors and are thought to arise as a neoplastic transformation of glial cells in the central nervous system. The prognosis for the disease is poor. Present treatment includes surgical resection of the tumor followed by radiation or chemotherapy. This application describes an attempt to develop alternative treatment strategies. The effectiveness of an adenovirus vector to deliver the herpes simplex virus thymidine kinase (tk) gene to inhibit selectively tumor cell growth upon receipt of ganciclovir (GCV) will be examined. The adenovirus vector will be specifically introduced into the tumor area by stereotactic injection; GCV will be administered systemically. The plan is to optimize growth inhibition by determining the effectiveness of redosing the vector and developing long term release of infectious virions into the surrounding environment.