Abstract: A portable stacking and nesting toilet comprises a small cup member which will nest inside a larger cup-shaped member, a seat member having a central opening, and a resilient sealing lid. The bottom of each cup has a raised lip which will engage the lip of the other cup and the open top ends of the cups have an annular rim. The seat member has a groove which engages the rim of the larger cup. In the stored position, the smaller cup nests inside the larger one and the bottom of the larger cup fits inside the seat opening. When assembled for use, the smaller cup is inverted with the resilient lid installed on its rim to serve as a non-skid base and the larger cup is installed upright on the inverted smaller one to engage the bottom lips. A watertight bag is placed in the upright larger cup with the open end of the bag folded over its rim. The seat is placed on the rim of the larger cup to secure the top of the bag on the cup rim and the toilet is ready for use.