ObjectiveThis study tested the new DSM-5 severity criterion for anorexia nervosa (AN) based on proposed body mass index (BMI) cut-points. MethodParticipants were a clinical sample of 201 treatment-seeking patients diagnosed with DSM-5 AN in Portugal. Participants were categorised based on DSM-5 severity levels and were compared on demographic and clinical variables assessed with the Eating Disorder Examination-Questionnaire. ResultsBased on DSM-5 severity definitions for AN, 73 (36.3%) participants were categorised as mild (17.0 BMI), 40 (19.9%) as moderate (16-16.99 BMI), 30 (14.9%) as severe (15-15.99 BMI) and 58 (28.9%) as extreme (<15 BMI). The severity groups did not differ significantly in age or gender. Analyses comparing the severity groups on measures of eating-disorder psychopathology revealed no significant differences on the Eating Disorder Examination-Questionnaire global or subscale scores. The groups also did not differ significantly on the frequency of binge eating or purging episodes within the past 28days. ConclusionsOur findings, in this clinical sample of patients with AN in Portugal, provide no evidence for the new DSM-5 severity ratings based on BMI level. Further research on the validity of the DSM-5 specifiers is needed and should test additional clinical or functional variables and especially prognostic utility for course and outcome across eating disorders. Copyright (c) 2017 John Wiley & Sons, Ltd and Eating Disorders Association.