Abstract: A pet litter box assembly is provided having an open-ended base into which litter can be placed, a cover which can be latched upon the base in order to seal the base and a waste collecting member mounted within the cover at a position spaced from the underside of the cover. When waste and used litter deposited in the base needs to be separated from non-used litter placed in the base, the cover can be seated upon and latched to the base and the pet litter box assembly can be rotated to cause the contents of the base to flow onto the waste collecting member. The waste collecting member includes numerous filtering orifices that are sized to permit non-used litter granules to readily flow therethrough while waste and used litter is collected in the waste collecting member for disposal. The base and the cover have double-wall constructions and therefore each includes inner and outer wall portions.