A litter box device for use by pets. The device includes at least two litter boxes arranged as stacked drawers held in a housing. The upper drawer is accessible to a pet through an entry to the housing. The bottom of each drawer has a screen and a slidably removable drawer bottom. Removal of the slidably removable drawer bottom allows the contents of the drawer to pass into the underlying drawer. After pets excrete waste into the litter in the top box, the loose litter is separated from the waste clumps by sliding the removable drawer bottom from the top drawer, allowing loose litter granules to flow down through a screened opening into the underlying drawer. The top drawer will retain the waste clumps on its screen within the upper drawer, the screen positioned proximate to the slidably removable drawer bottom. The waste clumps may then be removed from the drawer and screen. The lower drawer containing the filtered litter can be guided up into the top position. A lift assisting mechanism allows the lower drawer to be lifted into the upper drawer position without the operator having to bear the full weight of the litter-filled drawer. After the emptied drawer is placed in the vacant lower drawer position the apparatus is ready for pet use again.