Body dysmorphic disorder (BDD) is a distressing body image disorder that involves excessive preoccupation with physical appearance in a normal appearing person. Prior case reports of behavior therapy were encouraging, but no controlled evaluation of behavior therapy or any other type of treatment had been conducted. In the present study, 54 BDD subjects were randomly assigned to cognitive behavior therapy or no treatment. Patients were treated in small groups for eight 2-hour sessions. Therapy involved modification of intrusive thoughts of body dissatisfaction and overvalued beliefs about physical appearance, exposure to avoided body image situations, and elimination of body checking. Body dysmorphic disorder symptoms were significantly decreased in therapy subjects and the disorder was eliminated in 82% of cases at posttreatment and 77% at follow-up. Overall psychological symptoms and self-esteem also improved in therapy subjects.