An osteosynthetic pressure plate includes a slot formation for receiving a bone-fixing screw which is adapted to be secured to a bone part which is to be mended. The slot is formed with an edge which includes an oblique portion or ramp having an inclination such that when it is engaged by the underside of a head portion of a bone-fixing screw there will be a displacement of the pressure plate in a direction to move the ramp portion away from the fixing screw and to cause the plate to apply a pressure to hold the bone parts in tight engagement. The plate is advantageously useable with screws having heads of spherical form or conical form, for example. The inclination of the ramp and the configuration of the walls bounding the slot of the pressure plate are such that there will be a uniform and even shifting of the plate having the slot when the ramp of the walls bounding the slot is engaged by the screw head to cause the desired displacement of the pressure plate in order to displace the bone fragment toward tighter engagement with the adjacent bone fragment and into pressure engagement therewith.