OBJECTIVE: This study investigated the prevalence and phenomenology of body dysmorphic disorder in patients with obsessive-compulsive disorder. METHOD: The authors studied 442 patients who participated in the DSM-IV field trial for obsessive-compulsive disorder. RESULTS: Twelve percent (N = 51) of the patients had a lifetime comorbid diagnosis of body dysmorphic disorder. Patients with and without body dysmorphic disorder did not differ in demographic characteristics of obsessive-compulsive symptoms. Patients with obsessive-compulsive disorder and body dysmorphic disorder had more anxious, impulsive, and schizotypal features than patients with obsessive-compulsive disorder alone. Age at onset was similar for the two disorders, and severity correlated. However, insight was significantly more impaired for body dysmorphic disorder than for obsessive-compulsive disorder. CONCLUSIONS: As previously thought, these findings suggest that the two disorders are strongly related but also have differences that require further investigation.