The invention relates to a medical pump, especially for water jet surgery, in which the connection between a pump unit and a pump actuating device is improved and the operability of the pump is simplified. To this end, the medical pump comprises the following: a pump unit comprising at least one piston to be displaced in an associated cylinder; a pump actuating device comprising an openable and closable holding device for fixing and detaching the pump unit to or from the pump actuating device; openable and closable coupling devices for coupling or decoupling the piston to or from the pump actuating device; at least one drive device and a control system for actuating the pump unit by displacing the piston, the drive device being designed in a controllable manner for actuating, especially opening and/or closing, the holding device and/or the coupling devices in such a way that a working state or idle state is generated; a detection means which is connected to an inlet of the control system in a communicative manner and is embodied in such a way that it detects a state of use defining a pre-determined position relation between the pump unit and the pump actuating device, and transmits a first detection signal, describing the presence of the pump unit in the pump actuating device, to the control system for controlling the drive device; the control system for processing the first detection signal being embodied in such a way that it controls the drive device for generating the working state.