Stress response measured as the cortisol secretion rate as well as urinary 17 oxogenic steroid (17 OGS) and 17 oxosteroid (17 OS) excretion was investigated in a group of 28 patients with stroke (11 with hypertensive intracerebral hemorrhage and 17 with ischemic cerebrovascular insult). Significantly higher cortisol secretion values were found in the group of patients who died (p less than 0.01). Similarly, the first day urinary 17 OGS excretion pointed to the greater adrenocortical response in patients who died (p less than 0.05). Urinary 17 OS excretion was normal or below normal in the majority of patients and no difference was found between either male or female patients who survived or died. Our findings indicate that adrenocortical changes which maximize the production of cortisol are operative soon after the onset of stroke. The cortisol secretion rate appeared to be a good indicator of the severity of the stress caused by stroke and may be useful in predicting the prognosis of the illness.