Abstract: A pet litter box having a built in filter comprising a base portion which has a litter receiving area and a cover portion which has a screen member attached thereto, the screen member extending below the underside of the cover and being spaced therefrom to define a waste receiving pocket between the underside of the cover and the screening member. When it is desired to clean the litter box, the cover is placed on the base and the full assembly is rotated such that the used litter will enter the waste receiving pocket with the screen member filtering any clumping and/or solid material therefrom while permitting passage of the non used litter material back to the litter receiving area of the base portion; the cover may then be removed and the used litter discarded.