Abstract: A support assembly for mounting to a bed to position protective railings along the sides of the bed comprises one or more support members of flat, rigid material such as sheet metal. The support members are attached to the bed deck of a hospital bed or the frame of a standard bed with inwardly facing surfaces of the support members on opposite sides of the bed spaced by substantially the width of the mattress. A hollow sleeve is affixed to the support member to receive a terminal end of the railing. Relative dimensions and positional relationships are such that gaps between the rails and portions of the bed or mattress are minimized to reduce the possibility of a patient becoming wedged in such a gap. The side rail supports are essentially immune from mis-positioning due to poor training, errors or carelessness of personell attending to the bed and patient.