New approaches to transfer genetic material into tumor and normal central nervous system (CNS) tissues is being explored for various diseases of the CNS. The mechanisms involved in effecting antitumor activity using the suicide gene transfer approach are investigated. Targeting of tumoral vascular tissue, choroid plexus epithelium, and normal CNS structures is being pursued. New viral vectors, such as adenoviruses, are also being evaluated for therapeutic approaches in the CNS. Clinical studies to treat malignant brain tumors are underway and a clinical trial for treating patients with leptomeningeal neoplasia is pending.