A cognitive behavioural model of body image is presented with specific reference to body dysmorphic disorder (BDD). We make specific hypotheses from the model for testing BDD patients in comparison with: (i) patients with "real" disfigurements who seek cosmetic surgery; (ii) subjects with "real" disfigurements who are emotionally well adjusted; and (iii) healthy controls without any defect. There have been no randomised controlled trials of treatment for BDD and therefore the model has clear implications for the development of cognitive behavioural therapy. This was evaluated in a pilot controlled trial. Nineteen patients were randomly allocated to either cognitive behaviour therapy or a waiting list control group over 12 weeks. There were no significant pre-post differences on any of the measures in the waiting list group. There were significant changes in the treated group on specific measures of BDD and depressed mood. Cognitive behaviour therapy should be further evaluated in a larger controlled trial in comparison with another psychological treatment such as interpersonal therapy and pharmacotherapy.