We report on the case of a 15-year-old boy referred to Warrenstown inpatient unit for management of what appeared to be a typical case of anorexia nervosa. Over the course of his admission however, this diagnosis was no longer considered appropriate and substituted for a food avoidance emotional disorder. This is one of a number of cases of young males who have recently been referred for inpatient management of anorexia nervosa but which emerged into something quite atypical. The limited usefulness of the ICD-10/DSM-IV criteria in the diagnosis of an eating disorder in childhood and adolescence in this case reflects a broader level of discontent with the application of such diagnostic classification systems in a paediatric population.