Personality disorders (PD) are among the most common comorbid disorders in female patients with Anorexia Nervosa (AN). Recent research findings suggest that comorbid PD are associated with a higher treatment drop-out rate and a worse therapeutic outcome. However, no study to date has distinguished between certain age groups concerning these issues. Therefore, the present study focuses on the prevalence of PD (1), treatment drop-out rates (2) and weight gain (3) in female in-patients with AN. Thereby, we differentiate among three age groups (17-24 years; 25-34 years; 35-65 years). We assessed female in-patients (N=331) with AN at the Helios Clinic in Bad Grönenbach in Germany using the Eating Disorders Inventory-2 and the psychotherapeutic-medical basic documentation at the beginning and at the end of their treatment. Furthermore, we investigated the drop-out rate and weight gain by comparing anorexic patients with and without comorbid PD that were diagnosed by clinicians using ICD-10 criteria. In sum, our patients with AN demonstrated a prevalence rate of 34% for one or more comorbid PD. Interestingly, patients between 17-24 years showed a lower prevalence rate of 22% compared to those between 25-34 years (42%) and 35-65 years (41%). Furthermore, younger age and comorbid PD seemed to be significant predictors for treatment dropout. One of the most striking results was that younger patients (17-24) without a comorbid PD had the highest weight gain during treatment. This could not be observed in patients with a comorbid PD, who demonstrated the highest weight gain between 25 and 34 years of age. Our findings support the hypothesis that comorbid PD are related to a worse outcome in patients with eating disorders. Future studies might do well in assessing dimensional scores of personality disorders and other relevant aspects like for example the amount of social support to draw further conclusions on these associations. Our results emphasize the need for more disorder-specific interventions tailoring at patients with AN and comorbid PD to improve treatment outcome.