Abstract: Described herein is an inventive anti-splash guard for non-flush portable toilets. The innovation comprises a sloped structure either affixed to or made integral with the bottom of the holding tank of a portable toilet, positioned under the seat. The form of the inventive anti-splash guard is preferably conical, but may also be pyramidal, hemispherical and ellipsoidal. Functionally, the innovation may be submerged fully under the level of the holding tank water, so that the impact of deposited solid matter is absorbed by the anti-splash guard and not transferred to the surrounding water. In this way the upward splash of the water is suppressed, and risk of contamination to the user is greatly reduced. The disclosure describes both a portable toilet holding tank with an integrally formed anti-splash guard according to the invention, and stand-alone embodiments that may be retrofitted to existing portable toilets.