The authors have investigated the function of the hypothalamic-pituitary-adrenocortical (HPA) axis during and after withdrawal from alcohol. 24 hour rhythms of cortisol were abnormal in that elevated levels were seen throughout the day in patients with moderate to severe, but not mild, withdrawl. This abnormality of circadian secretion of cortisol, which is similar to that seen in Cushing's syndrome and post-operative trauma, returned to normal after a period of one week of abstinence on their in-patient ward. Such excessive secretion of cortisol may explain some of the complications of chronic alcoholism.