Brain metastases have traditionally been treated with a surgical or radiotherapeutic approach. Chemotherapy is used occasionally as salvage therapy. The blood-brain barrier excludes most chemotherapeutic agents, rendering many systemic options ineffective within the CNS. Intrathecal chemotherapies do not penetrate into brain tissue or bulky parenchymal tumors, so are ineffective in treatment of brain metastases. However, some patients with brain metastases benefit from chemotherapy, and temozolomide or targeted therapies like gefitinib have demonstrated activity. A better understanding of the biological behavior of brain metastases may lead to development of effective treatments for this common complication of systemic cancer. The review discusses the biology of brain metastases and provides an update on current chemotherapeutic strategies.