A mattress intended for use in hospital facilities, and having replaceable parts is disclosed. The mattress is made up of an upper layer of one foam material and a lower thicker layer, itself having two layers. The first lower layer is constructed to give a reclining body flexible support. The second lower layer supports and acts as a base for the first lower layer. The upper and lower foam layers are covered by a water and moisture impervious cover. The cover is formed in two halves, an upper half enclosing the upper layer on the top and sides and a lower half enclosing the lower layer on the bottom, the sides and a portion of the top. The two halves of the cover are joined together by a zipper around the side walls of the mattress to entirely enclose two inner foam layers.