Background: Recent studies have confirmed a significant comorbidity between eating disorders and self-harm; they linked the presence of self-harm to a more severe and treatment-resistant eating disorder symptomatology. Difficulties with impulse-control were suggested to mediate this association. The present study explored another variable believed to be involved: mentalising. Method: A cross-sectional, questionnaire-based, between-groups design was employed and a measure of mentalising was compared in individuals presenting with eating disorders and in individuals presenting with eating disorders and concurrent self-harm. Both groups were compared with a control group. Results: Findings suggested that individuals with concurrent presentations reported less mentalising ability compared to individuals without concurrent difficulties. In addition, both groups significantly differed from the control group. Conclusions: Results are discussed in relation to clinical implications.