In 1980 and 1987, 112 patients received a principal diagnosis of anorexia nervosa during their first admission to a psychiatric unit in New Zealand. Over the subsequent 5 years 48 (43%) were readmitted to hospital on one or more occasions, with those who were 16 years or less being more likely to be readmitted. These patients with anorexia nervosa spent longer in hospital for each admission than any other group of psychiatric patients with non-organic disorders, and over the 5-year follow-up the average cumulative length of stay was exceeded only by patients with schizophrenia and organic disorders. These findings suggest the need for further study into the best treatment setting for patients with anorexia nervosa, and to what extent chronicity in anorexia nervosa may be reduced.