Abstract: A cage system for laboratory animal care has a plastic cage with a molded perforated-bottom, a snap-on plenum cage top, a cage top feeder lid and a snap on waste tray. The floor of the cage is shaped with rounded perforations and domed protrusions to deflect both liquid and solid waste down to the attached waste tray. A filtered air supply is introduced into the lid of the cage and passes through orifices in the bottom of the lid, flowing laminarly through the body of the cage and out perforations in the floor over the waste tray. A water supply system for the cage is provided. No bedding is required in the cage. The system is air tight and air in any one cage is isolated from air in all other cages in the system which can be mounted on a rack. A drain for liquids is provided in the waste tray. In an alternate embodiment, the cage has an imperforate floor. A plurality of cages are supported in a rack. Several configurations to support the cage within the rack are provided.