Abstract: A modular flooring system for an animal housing is provided, the flooring being particularly suited to pig housings due to the structure of the flooring which minimizes spacings in which manure, and its attendant bacteria, could collect. A plurality of interconnecting interior and straight-edge panels are provided and a plurality of panel support units each unit comprising a device for fixing the unit to a substrate of the housing and a device for engaging at least one panel to support the panel over the substrate. The panels each have a rectangular frame having side, top and bottom members and a plurality of spaced horizontal and vertical members extending between the side and top and bottom members of the frame, respectively, forming a plurality of horizontal slots. Each side member comprises means for coupling the panel to an adjacent panel. In the interior panels the outer configurations of the top and bottom members are mirror images and the interior panels are rotatable.