Background: Patients with Trichotillomania (TC) have an irreversible urge to pull their hair. This self-mutilation behavior is associated with high level of tension before and a sense of gratification and relief after TC. Objective: To investigate the personality characteristics of patients suffering from TC. Method: The study was performed on 43 TC patients and 43 gender and age-matched non-psychiatric control individuals who were asked to complete a Persian version of the NEO Personality Inventory-Revised (NEO PI-R). Results: The TC patients had significantly higher scores on Neuroticism (p<0.0001) and Agreeableness (p<0.05) domains. The TC patients were high scorers in all Neuroticism subscales including anxiety, angry-hostility, depression, self-consciousness, impulsivity, and vulnerability to stress. The patient group had lower scores on the compliance scale, a subscale of Agreeableness. Conclusion: According to Costa and McCrae (founders of the NEO PI-R) suggestions, the picture of the personality traits or characteristics displayed by our data resembles borderline personality disorder.