Objective: The aim of this study was to examine the impact of childhood sexual abuse (CSA) on clinical characteristics and premature termination of treatment in anorexia nervosa (AN). Method: The participants were 77 consecutive patients with AN admitted to an inpatient eating disorders unit. The patients were assessed in terms of eating disorder symptoms, general psychopathology, and CSA history at admission to hospital. Results: Thirty-seven patients (48%) reported a history of CSA before the onset of the eating disorder. Individuals with a history of CSA reported significantly greater psychiatric comorbidity, including higher levels of depression and anxiety, lower self-esteem, more interpersonal problems, and more severe obsessive-compulsive symptoms. Patients with the binge-purge subtype of AN (AN-BP) were significantly more likely to report a history of CSA prior to the onset of the eating disorder as compared with patients with the restricting subtype (AN-R) of the illness (65% of the AN-BP patients vs. 37% of the AN-R patients; p is less than 0.02). Contrary to our predictions, abused patients were not significantly more likely to dropout of treatment overall. However, patients of the binge-purge subtype (AN-BP) with a history of CSA were significantly more likely to terminate treatment prematurely as compared with the other patients. Conclusions: Consistent with previous findings, the present results indicate that the prevalence of CSA is high among individuals seeking inpatient treatment for AN. A history of CSA was associated with greater psychiatric disturbance overall and a higher rate of dropout for patients of the binge-purge subtype.