Body dysmorphic disorder (BDD) by proxy is a body image disorder that causes great discomfort to the patient and significant others. Patients suffering from this condition are preoccupied with dissatisfaction about the other person's appearance. There is very little research on the treatment of this disorder. This paper presents a description of the cognitive behavioral treatment of a case of BDD by proxy. The patient is a 36-year-old male who exhibited extreme dissatisfaction with his spouse's appearance. Thirteen sessions of cognitive behavior therapy were supplemented with couple interventions and a trial of pharmacotherapy. Treatment effects were evaluated using an adapted version of the BDD-YBOCS to establish the severity of BDD by proxy, and the Symptom Check List (SCL-90) as a general measure of psychopathology. Visual inspection of the data and the calculation of Reliable Change Indices (RCI) showed that CBT led to a clinically significant reduction in BDD by proxy symptomatology (RCI = 10.6), and in anxiety, depression, and obsessionality. In addition, according to clinical impressions, marital functioning also improved to a considerable extent. This case description is the first to suggest the potential benefits of CBT for BDD by proxy.