In contrast to other non-psychotic psychiatric populations, subjects with obsessive-compulsive disorder (OCD) are more prone to have personality disorder from cluster A (the odd and eccentric cluster). The present study aims at further investigating the relationship between these and other personality traits in OCD subjects and their relation to high functioning autism (HFA) and Asperger disorder. Sixty-four subjects with OCD were included. Personality traits were assessed with the Karolinska Scales of Personality (KSP), and personality disorders with DSM-adapted questionnaires. In addition, autistic traits were assessed in 29 videotaped subjects, by 3 independent raters. Twenty percent of the subjects with OCD were identified as also having autistic traits. These subjects scored higher on KSP scales measuring muscular tension, psychasthenia, and inhibition of aggression and lower on socialization as compared with OCD subjects without autistic traits. Additionally, subjects with autistic traits fulfilled criteria for anxious personality disorders and paranoid personality disorders significantly more often than subjects without autistic traits. We propose that OCD is often related to HFA and Asperger disorder. Self-report questionnaires may be useful in establishing the diagnosis. However, those with the most obvious autistic features seem to be less able to identify these traits in themselves.