Abstract: A mattress supporting foundation unit which is constructed to offer very firm support to a mattress, and which includes a base frame, a horizontal wire mesh spaced above the frame, and support wires for connecting the mesh to and supporting it from and above the frame, with these support wires having portions forming legs which extend upwardly from the base to the mesh and are substantially straight for their entire length between the base and mesh to give the desired rigidity to the overall structure. The support wires desirably also have connector portions which extend laterally between successive legs and are attached to the base and mesh.