Abstract: A positioning aid for surgical procedures has a carrier system and a template. The carrier system consists of a carrier plate, which is provided with a recess, and supports. The carrier plate can be secured to a cranial bone via the supports over an operating field for the surgical procedure. The template has a template plate which can be connected to the carrier plate in a play-free manner and which comprises a guiding aperture. The guiding aperture is arranged and oriented in the template plate, which consists of a blank, in an individualized manner according to coordinates ascertained in advance. The central longitudinal axis of the guiding aperture matches a trajectory for accessing the operating field for the surgical procedure when the carrier system and the template are assembled and the carrier system is secured to the cranial bone.