A positioning device for positioning a patient when being radiographed with a panorama X-ray machine 10 includes a retainer 18 disposed in a fixed direction relative to the X-ray apparatus 10 and a variable positioner connected thereto, for example a bite block 19 or a support, the retainer including a longitudinal guide 20 for guiding the positioner 19 such that the positioner 19 is guided in the retainer 18 for vertical adjustment in a longitudinal direction.