Studies examining the function of the hypothalamic-pituitary-adrenal (HPA) axis in anorexia nervosa are reviewed. A principal finding is that of hypercortisolism, associated with increased central corticotropin-releasing hormone levels and normal circulating levels of adrenocorticotropic hormone. Similarities between neuroendocrine findings in anorexia nervosa and in affective disorder are reviewed. The contribution of circadian rhythm disturbances and malnutrition to observed HPA axis abnormalities in anorexia nervosa is also considered. Directions for future research are discussed.