A restraint assembly for holding a portion of a patient in a fixed position on or relative to an X-ray table for the taking of X-rays is disclosed. The assembly comprises a restraint and restraint support. The restraint is usable with or without the restraint support and includes a platform which has a plurality of suction cups for mounting the platform to the X-ray table, the restraint support, or any other planar surface. A padded surface overlies at least a portion of the platform and is adapted to receive and support the portion of the patient to be restrained thereupon. A pair of sidewalls are attached to the platform on opposite sides of the padded surface and can be moved together to secure the portion of the patient to be restrained therebetween. If desired, a pair of slots can be formed in the platform on the opposite sides of the padded surface and a strap passed through the slots and around the portion of the patient to be restrained to further secure that portion of the patient and hold it in a fixed position. The restraint support includes a backplate that can be removably mounted perpendicular to the X-ray table and a frontplate slidably coupled parallel and adjacent to the backplate for vertical movement relative to the table. The restraint can be mounted to the frontplate of the support and then positioned a predetermined distance above the X-ray table.