The purpose of this study was to determine the effectiveness of a parent training program for teaching toilet skills to children with autism and mental retardation. The study was conducted with three mothers and their children. A multiple probe design using probe sessions across subjects was used. The experimental procedure consisted of two meetings and a home visit. Results of the study showed that children achieved the target skill independently. They continued to use the skill during the follow up phase. Overall findings indicated that the parent training program was effective for teaching toilet skills for children with autism and mental retardation. (Contains 1 figure.)