Individuals with body dysmorphic disorder (BDD) have been postulated to have schizoid, narcissistic, and obsessional personality traits and to be sensitive, introverted, perfectionistic, and insecure. However, data on personality traits and disorders in BDD are limited. This study assessed 148 subjects with BDD, 26 of whom participated in a fluvoxamine treatment study; 74 subjects were assessed for personality disorders with the Structured Clinical Interview for DSMIII-R Personality Disorders (SCID-II), 100 subjects completed the NEO-Five Factor Inventory (NEO-FFI), and 51 subjects completed the Rathus Assertiveness Scale. Forty-two subjects (57%) had one or more personality disorders, with avoidant personality disorder (43%) being most common, followed by dependent (15%), obsessive-compulsive (14%), and paranoid (14%) personality disorders. On the NEO-FFI, the mean scores were in the very high range for neuroticism, the low range for extraversion and conscientiousness, the low-average range for agreeableness, and the average range for openness to experience. On the Rathus Assertiveness Scale, the mean score was -17.1 +/- 32.0 for women and -17.0 +/- 32.3 for men. Among fluvoxamine responders, the number of personality disorders significantly decreased between the study baseline and endpoint. These findings suggest that the rate of personality disorders in BDD is relatively high, with avoidant personality disorder being most common. The high neuroticism scores and low extraversion scores are consistent with this finding.