Abstract: A permanently implantable, fixable positioning system (1) for stationary attachment to a human body, without play, preferably to the human skull. It has ball-and-socket joint (3), linear axle (4) fixed stationary to it, and a carriage (5) which is guided on the linear axle for accommodating an implantable actuator or sensor device (6). The combination of the axial degree of freedom of the linear axle (4) with three degrees of rotational freedom of the ball-and-socket joint (3) allows a surgeon four-axis, in-situ positioning of the implantable means especially in the middle ear and mastoid cavities. By using the positioning system, precise positioning of a free active end (16) of the implantable device (6) relative to sensitive anatomical structures of the human body is enabled while avoiding risky relative movements between the implantable device and the body of the patient. The positioning system is thus used more or less as a "tremor-free artificial hand" of the surgeon.