Abstract: Apparatus for positioning the body of a patient in relation to equipment for contactless comminution of concrements such that the focal point of equipment is made to coincide with a concrement; the patient who lies on a rest which is moved with the patient on it in a longitudinal direction, tilted about it, and moved also laterally and in a direction that is transverse to the longitudinal and lateral directions of movement; a water filled cushion with controlled water level is adapted for interpositioning between the equipment for comminution and focusing, and the patient, a plurality of differently oriented X-ray beams are provided for locating a concrement in the patient and images are marked through a light pen or the like on X-ray monitors; a control provides for homing-in the rest in relation to the comminution equipment such that its focal point coincides with the concrement as previously detected.