A litter box includes upper and lower shells having corrugations formed therein that strengthen the walls of the shell and that enable the walls themselves to be relatively thinner than would be required in the absence of corrugations. The relatively thinner walls thus enable the litter box to be formed from less material. The corrugations are configured to enable molding with conventional two-part molds. An upper shell portion has a handle integrally molded therein. When assembled, the upper shell sits atop the lower shell, and the line of junction between the upper and lower shells is oriented oblique to a bottom surface of the lower shell and thus oblique to a floor upon which the litter box may sit. The oblique angle enables a relatively low step-over height at the front and a relatively high height at the rear to resist the penetration of urine.