Fifteen women with borderline personality disorder who do not experience pain during self-injury were found to discriminate more poorly between imaginary painful and mildly painful situations, to reinterpret painful sensations (a pain-coping strategy related to dissociation), and to have higher scores on the Dissociative Experiences Scale than 24 similar female patients who experience pain during self-injury and 22 age-matched normal women. ‘Analgesia’ during self-injury in borderline patients may be related to a cognitive impairment in the ability to distinguish between painful and mildly painful situations, as well as to dissociative mechanisms.