This is a prognostic study on 41 patients with anorexia nervosa (including three males) who satisfied defined diagnostic criteria. The patients had all been admitted to a metabolic unit where the mainstay of treatment was nursing care aimed at rapid restoration of body weight. A follow-up was conducted after a minimum lapse of four years after each patient's discharge from hospital. The outcome of the patient's illness was expressed in terms of an 'average outcome score' and a 'general outcome'. The series included a relatively high proportion of patients with a long illness who had received previous psychiatric treatment. Their families tended to come from higher social classes; a disturbed relationship with the patient was frequent. Premorbid disturbances in personality development were also common. The immediate response to treatment was excellent, with the majority of the patients returning to a normal weight, but relapses after discharge were common and readmissions were necessary in half the patients. At follow-up, the patients fell into the following defined categories: 'good' (39%), 'intermediate' (27%), 'poor' (29%), died (5%). Most of the patients who failed to recover continued to display the clinical features characteristic of anorexia nervosa. Among predictors of an unfavourable outcome were found a relatively late age of onset, a longer duration of illness, previous admissions to psychiatric hospitals, a disturbed relationship between the patient and other members of the family, and premorbid personality difficulties. It is suggested according to the severity of their illness, rather than on the method of treatment itself. The illness may last several years before eventual improvement or recovery, and a follow-up study must be extended over at least four years to be meaningful. An accurate prediction of eventual outcome is almost impossible, but late recoveries justify an optimistic outlook and continued therapeutic endeavour.