The aims of the present study were to examine the frequency of personality disorders in 36 patients with obsessive-compulsive disorder (OCD), and to investigate whether patients with a coexisting personality disorder could be characterized by certain personality traits assessed by means of the Karolinska Scales of Personality (KSP). In total, 27 (75%) of the OCD patients fulfilled the DSM-III-R criteria for a personality disorder, and 13 patients (36%) had an obsessive-compulsive personality disorder. Subjects with a comorbid personality disorder had significantly higher scores on most of the KSP scales, including all anxiety scales, as well as scales measuring indirect aggression, irritability, guilt and detachment, whereas subjects without personality disorders did not differ significantly from healthy controls with regard to personality traits.