The invention is related to an operating device for apparatus combinations of medical-technical system workplaces, especially for the minimal invasive surgery. The individual apparatus of the apparatus combination are connected to a computer (28) having a monitor (30) and driven by way of foot-actuated actuating members. In order to improve the usability and flexibility, an actuating member fashioned to be a foot roller (56) provides computer compatible signals, while at least one further actuating member is formed to be a foot switch (58,60) and can be assigned to one of the apparatus-specific functional elements software-controlled by the actuation of the foot roller (56). A switch assignment field (88,90) assigned to the foot switch (58,60) for the symbolic display of the functional element assigned to the foot switch (58,60) at that time is provided on the monitor (30).