Advances in molecular biology and recombinant DNA technologies have contributed to our understanding of the molecular basis of many diseases. Now the possibility of gene transfer into normal cells to produce a gene product of therapeutic potential, or into diseased cells to correct the pathologic alteration, promises to revolutionize medical practice. In contemporary medicine, many therapeutic strategies focus on the link between a biochemical deficiency and the ensuing disorder. The treatment of noninfectious disease is often based on replacement therapy; medication is given to compensate for biochemical defects and to prevent or reverse the progression of disease. Although conventional therapies seldom alter the fundamental cause of a disease, gene therapy potentially could correct, at a molecular level, the genetic abnormalities contributing to its pathogenesis. Treatment directed at specific molecular alterations associated with the development of neurologic disease provides expectations of more effective and less toxic therapy. The development of gene therapy for nervous system tumors has progressed rapidly and may be prototypical in the development of therapies for inherited and acquired disorders of the nervous system. We describe possible strategies for using gene therapy to treat nervous system disorders, and we review recent advances in gene therapy for nervous system tumors.