Anorexia nervosa (AN) mainly affects girls or women between 13 and 45 years of age. According to previous studies, one of the reasons for the desire to be thin is low self-esteem. The purpose of the study was to examine the self-esteem of 38 female patients with AN between 16 and 25 years of age, before and after 3 months of treatment at a specialist ward for eating disorders in Göteborg, Sweden. A quantitative pre- and post-assessment based on two self-rating questionnaires, the Rosenberg Self-Esteem Scale (RSE-S) and three subscales (weight phobia, body dissatisfaction, and ineffectiveness) of Eating Disorder Inventory-2 (EDI-2), together with body mass index (BMI), were used in the study, which was conducted between June 2005 and March 2008. The results reveal that self-esteem, BMI, weight phobia, and body dissatisfaction improved significantly between pre- and post-treatment. The RSE-S and EDI-2 ineffectiveness correlate highly with one another, which lends support to convergent validity, and the internal consistency was high for both the RSE-S and EDI-2 ineffectiveness. The results indicate that the treatment was effective, as both patients' self-esteem and BMI increased after completed treatment, which was the primary goal of the treatment at this ward. Future studies should focus on follow up and the way self-esteem manifests itself at different points in time within an individual.