We report the case of a 7-year-old boy who had autism spectrum disorder and displayed disruptive and avoidant behavior when using the bathroom at home with people present in adjoining rooms or nearby the bathroom door. Desensitization treatment was implemented by gradually exposing the boy to proximity of an in-home therapist when he was in the bathroom and positively reinforcing the absence of disruptive behavior. Treatment effectively eliminated bathroom avoidance and generalized to settings outside the home. Intervention outcome was maintained 6- and 7-months post-treatment.