Background. We measured psychopathic traits in boys with autism spectrum disorder (ASD) selected for difficult and aggressive behaviour. We asked (i) whether psychopathic tendencies can be measured in ASD independent of the severity of autistic behaviour; (ii) whether individuals with ASD with callous–unemotional (CU) traits differ in their cognitive profile from those without such traits; and (iii) how the cognitive data from this study compare with previous data of youngsters with psychopathic tendencies.

Method. Twenty-eight ASD boys were rated on psychopathic tendencies, autistic traits and a range of cognitive measures assessing mentalizing ability, executive functions, emotion recognition and ability to make moral–conventional distinction.

Results. Our results indicate that psychopathic tendencies are not related to severity of ASD. In addition, such tendencies do not seem to be related to core autistic cognitive deficits, specifically in ‘mind-reading’ or executive function. Boys with co-occurring ASD and CU tendencies share some behaviours and aspects of cognitive profile with boys who have psychopathic tendencies alone.

Conclusions. Callous/psychopathic acts in a small number of individuals with ASD probably reflect a ‘double hit’ involving an additional impairment of empathic response to distress cues, which is not part and parcel of ASD itself.