Nonsuicidal self-injury (NSSI) refers to the direct and deliberate destruction of one's own body tissue in the absence of lethal intent. The Inventory of Statements about Self-Injury (ISAS) is a recently developed instrument that taps both the frequency of different forms of NSSI and the self-perceived functions of the behaviour. The purpose of the present pilot study was to use the ISAS to study the functions of self-injury in a group of women with severe forms of NSSI who were treated within Swedish residential care settings and also to compare the patients' views with their therapists' views concerning these functions. Consistent with previous research, the patients reported intrapersonal functions (e.g. affect regulation and self-punishment) as more relevant than interpersonal functions (e.g. interpersonal influence and peer bonding). The therapists' ratings differed little from the patients' self-reports, although significant differences were found for some functions: The patients rated self-care and toughness as more important than the therapists did; the therapists, on the other hand, rated interpersonal influence and the marking of distress as more relevant than the patients did. Although the present study did not contain a full validation of the Swedish version of the ISAS, the results showed good internal consistency for the interpersonal and intrapersonal factors of the Swedish version.