OBJECT: In January 1998 the Guidelines and Outcomes Committee of the American Association of Neurological Surgeons (AANS) issued a charge for the development of evidence-based practice parameters focusing on the treatment of patients with single metastasis to the brain. The charge was imposed in response to the significant controversy surrounding questions relating to the optimal management strategies for patients with single brain metastasis. METHODS: A team consisting of physicians from the AANS, the American Academy of Neurology, and the American Association of Therapeutic Radiation Oncology convened and the literature was reviewed. Methodically drawing from the best of Class I, II, and III levels of available evidence, authors sought to determine how the literature addressed and disposed of the question of the optimal management for an adult with a known history of cancer and a single metastatic brain lesion. Framing the question in this specific manner allowed researchers to focus directly on treatment issues, without having to consider diagnostic issues. CONCLUSIONS: The results of the evidence-based analysis demonstrated that there was insufficient information to establish standards of care. Data from the literature does, however, support a guideline stating that surgical resection accompanied by whole brain radiation therapy is associated with the best survival rate. Additional lower-quality evidence supports an option for management with radiosurgery.