Brain metastases are ten-times more common than primary brain tumors and are a common complication in patients with systemic cancer. The most common sources of brain metastases are lung and breast cancers, although in 15% of patients, the primary site is unknown. Optimal treatment is dependant upon tumor location, size, number of tumors and status of the systemic disease. Currently, management of brain metastases with surgery, radiotherapy and stereotactic radiosurgery is known to improve the quality of life and even life expectancy for selected patients. Techniques under investigation include focal radiation techniques, magnetic resonance imaging guided thermal ablation of metastases, drug delivery modes that bypass the blood-brain barrier and novel drug and molecular therapeutics. Efforts are ongoing to understand the molecular biology of brain metastases.