The objective of this report was to describe an efficacious treatment of an adult with long-standing anorexia nervosa (AN). A 50-year-old woman with an over 7-year history of AN and comorbid major depression had been treated unsuccessfully with numerous psychotropic medications, manualized cognitive behavior therapy, and an intensive outpatient treatment program before referral. After treatment with mirtazapine, she gained weight and her depression improved. A 9-month follow-up revealed a maintenance of these benefits. Mirtazapine may be useful for older, chronically ill patients presenting with AN and comorbid depression. © 2010 by Wiley Periodicals, Inc.