Abstract Background Delusional characteristics have been largely ignored in patients suffering from anorexia nervosa (AN). Objectives To review the literature on delusional features in AN from phenomenological, neurobiological, and clinical viewpoints. Methods Data were obtained through searches of Medline, PubMed, SciELO and Cochrane Library. Results Distorted beliefs in AN may range from an overvalued idea to an overt delusion, involving affective, personality and/or psychotic disorders. Studies confirm alterations in monoaminergic systems. It has also been seen a decreased integration of visual/proprioceptive information, and alterations in neural networks involved in body processing. It is known that body image distortion may present “delusional proportions” as a consequence of great concern about body. Concomitantly, “embodied defence hypothesis” has been proposed. Restrictive AN exhibits higher levels of delusionality, and a particular delusional type of AN has been suggested, associated with a worse long-term outcome. Low doses of atypical antipsychotics are recommended combined with cognitive techniques. Discussion Delusional thinking in AN is likely a dynamic and dimensional phenomenon that can vary, both in nature and/or severity, whereas high insight levels, before and after refeeding, result in positive outcomes. Neurobiological research on this topic must be encouraged, since clinical and phenomenological approaches are comparatively more frequently reported.