BackgroundDysmorphophobia may improve after a variety or combination of treatments, but which elements of a treatment are useful is usually not certain.MethodIn a single out-patient case study rational role-play (‘paradoxical discourse’) was added to exposure plus cognitive restructuring (CR) for a dysmorphic delusion study comprised of 20-minute sessions one week apart.ResultsPrevious exposure plus attempted CR had improved anxiety, phobias, work and social leisure, but not dysmorphic belief. Added brief rational role-play was followed by resolution of the dysmorphic belief. All measures remained much improved at 18-month follow-up.ConclusionsRational role-play deserves a controlled trial in dysmorphophobia and other problems and exploration of its mechanism of action.