The comorbidity between anorexia nervosa (AN) and bipolar disorders (BD) among subjects with AN is a matter of some debate, regarding its existence, its impact on the clinical manifestations of AN and the nature of the relationship between these disorders. Our aims were: (1) to evaluate the prevalence of BD among patients with severe AN; and (2) to determine whether people with a history of BD present particular clinical AN characteristics in comparison to people with a comorbid major depressive disorder or with any mood disorder comorbidity.