Evidence links high levels of Autism Spectrum Disorder Traits in women with chronicity of anorexia nervosa. This study reports through clinical audit the impact of ASD traits on treatment outcomes of girls who were referred for treatment in a specialist eating disorder service. Presence of current, but not early childhood, ASD traits was elevated in comparison with previously reported community samples. Current ASD traits were correlated with emotional disorders and with need for treatment augmentation (psychiatric inpatient or day patient admission), but this relationship was not significant after the contribution of depression had been controlled for. There was no difference in Morgan Russell Outcomes at discharge for those with high and low current ASD traits. Parent-reported ASD-related developmental difficulties were associated with attenuated change in self-reported cognitive symptoms of AN. This study highlights the need for further understanding of the aetiology, diagnostic significance and predictive utility for future relapse of elevated ASD traits in childhood eating disorders. Copyright (c) 2017 John Wiley & Sons, Ltd and Eating Disorders Association.