Abstract: An implantable pump, actuated by the patient in whom the pump is implanted, to provide pain relief and/or other therapeutic benefits. There is disclosed a fully implantable pump system, including a reservoir for holding fluid, a septum by which the reservoir is periodically refilled, and a resilient pump chamber responsive to manual pressure, for delivering limited amounts of the fluid through a catheter to a specific location within the body of the patient. Alternative embodiments disclosed include designs incorporating "windkessel-like" devices for controlling discharge of the fluid to the specific location to occur over extended time periods at relatively constant flow rates.