--- - |2+ Abstract Objective To evaluate symptom change among adolescents with anorexia nervosa (AN) receiving a novel program of family based treatment (FBT) combined with a cognitive behavioural therapy (CBT) module on perfectionism (FBT + CBT‐P). Methods A cohort study was conducted with 21 adolescents with AN who entered FBT + CBT‐P; 19 adolescents completed treatment (an average of 32 sessions). Participants completed four repeated assessments over 1 year, which included measures of eating disorder symptoms and perfectionism, self‐orientated perfectionism, and socially prescribed perfectionism (SPP). Results Using intent‐to‐treat analyses, group means showed significant increases in weight, and decreases in symptoms and perfectionism (except SPP) at the third assessment (following CBT) and at the end of FBT + CBT‐P treatment, relative to pre‐treatment. Of the completing participants, more than half improved on all measures (except SPP), and all participants improved in weight. Discussion FBT + CBT‐P was associated with average declines in adolescents’ eating disorder symptoms and perfectionism, and improvements in perfectionism were associated with improvements in eating disorder symptoms. A randomised controlled trial should be conducted to compare the efficacy of FBT to FBT + CBT‐P, including follow‐up to assess length and rate of symptom remittance or time to relapse. - Clinical Psychologist, EarlyView.