Poor cognitive flexibility and perfectionism are common features in anorexia nervosa (AN). The current study aimed to investigate cognitive flexibility and clinical perfectionism as potential predictors of AN. Twenty women with a current diagnosis of AN ( age = 28.25, = 7.62) and 170 community participants with no lifetime history of an eating disorder ( age = 29.23, = 9.88) took part in an online cross-sectional study that included self-report questionnaires of cognitive flexibility and clinical perfectionism. It was found that compared to the community sample, women with AN self-reported significantly poorer cognitive flexibility and significantly greater clinical perfectionism. In a regression model, clinical perfectionism (but not self-reported cognitive flexibility) significantly predicted group membership. The specificity and sensitivity of the model were high. These preliminary findings indicate that clinical perfectionism may represent a key feature of AN and may accurately discriminate between participants with and without AN, though more research is required.