A major obstacle to the effective systemic therapy of intracranial malignancies and infections, the bloodbrain barrier was overcome by the development of the Ommaya reservoir in 1963. Initially used in treating cryptococcal meningitis, this closed system for continued access to the ventricular spaces has a variety of applications. They include treatment of cancer pain, chronic or recurrent CNS infection, prophylaxis of CNS involvement in acute lymphoblastic leukemia, and treatment of leptomeningeal malignancy. The authors outline the rationale, latest indications, surgical technique, and potential complications arising from the use of the Ommaya reservoir and other such subcutaneous reservoirs.