Abstract: A thermally controlled mattress construction including a mattress body designed to support a person lying on top thereof. A removable pillow top for the mattress body, removably fastened along the peripheral edges, incorporates a thermally controlled liner as an integral but removable part thereof. The liner is removably fastened to the bottom of the top surface by a fastener extending along the lower peripheral edge of the pillow top, and also the pillow top is removably fastened to the mattress body by a fastener extending along its peripheral edge. This arrangement provides for removal of the liner for repair of maintenance or other reasons. In one embodiment, the thermally controlled liner includes an electrical heater, which can incorporate two separately controllable heaters, one for each half side of the mattress. In a second embodiment, the thermally controlled liner includes therein an array of tubing, through which either heated or cooled fluid is pumped to selectively heat or cool the pillow top.