Recent reports have postulated the existence of two different types of self-injurious behavior: impulsive and compulsive. The aim of the present study is to analyze the dimensionality of self-injurious behavior and to study the link between self-injurious behavior and clinical features in anorexia nervosa. The study involved 236 consecutive patients with anorexia nervosa, diagnosed by DSM-IV criteria. Subjects were evaluated by means of a semistructured interview and self-reported questionnaires, such as the Eating Disorders Inventory and Hopkins Symptom Checklist. A principal component analysis was used to study the dimensionality of different types of self-injurious behavior, including purging. Our findings confirm the distinction between impulsive and compulsive self-injurious behavior. The dimensions appear to be represented as a continuum in both the anorexia nervosa diagnostic subgroups. A third distinct dimension emerged that included self-induced vomiting and laxative/diuretics abuse. Childhood sexual abuse and anxiety significantly predict the presence of impulsive self-injury, whereas obsessionality and age predict compulsive self-injury. The coexistence of a positive score on both dimensions of self-injurious behavior was the strongest predictor of treatment dropout. The present study highlights the importance of self-injurious behavior; it should be given due consideration in future outcome studies on anorexia nervosa