1. The temperatures of thermal stimuli which evoked a feeling of maximal pleasantness upon contact with the hands of 14 malnourished patients with anorexia nervosa and 19 control subjects have been determined. A uniform skin temperature of 35°C for all individuals studied was achieved by immersion of the subjects and patients in water at that temperature. Core temperatures of the anorexic patients were similar to those of the control subjects, but six of the patients preferred temperatures that were significantly higher than those of the control subjects. The thermal preferences of the remainder of the patients were similar to those of the control subjects.
2. The abnormally high thermal preferences of some of the anorexic patients could not be attributed to abnormal thyroid status, since values for serum free thyroxine measured in this group were similar to those obtained for the remaining patients. The abnormal responses persisted after there had been a substantial gain in the patients'weight and did not therefore appear to be directly due to malnutrition.
3. Elevation of deep body temperature produced an expected shift in preference towards lower stimulus temperatures in a sample of subjects from the control group, and in the patients who had initially preferred temperatures within the range of the controls. In the patients who had initially preferred abnormally high stimulus temperatures, however, hyperthermia produced little change in thermal preference.
4. It is suggested that an elevation in the set-point temperature for behavioural thermoregulation can occur in some patients with anorexia nervosa, and that this displacement-5-contribute to the distressing sense of cold which some patients experience.
