The invention is directed to a pet litter box that has a lower portion shell assembly and an upper portion shell. The upper portion shell assembly includes an opening onto a grate floor which a pet has to walk across to gain access to the litter below in the lower portion shell. The grate floor and an associated dividing wall are couple directly to and with the upper portion shell such that when the upper portion is removed from the lower portion shell, the grate floor and dividing wall are removed with it giving full access to the litter below. The grate floor is typically comprised of an expanded metal grate.
