Sheehan's syndrome is thought to be caused by pituitary necrosis associated with massive hemorrhage at delivery. We report here on a patient with Sheehan's syndrome, showing a rare type of panhypopituitarism suggesting dysfunction of both the hypothalamus and the pituitary. Although the basal level of plasma ACTH was normal, that of plasma cortisol was low. ACTH showed a delayed high response to CRH and a low response to insulin-induced hypoglycemia, while plasma cortisol showed a low response to CRH and no response to insulin-induced hypoglycemia. In the standard ACTH test, a normal rise of plasma cortisol was found. These results indicate that the primary site responsible for hypothalamic-pituitary-adrenocortical hypofunction may be the hypothalamus. In addition, the dysfunction of the pituitary itself is suggested by the hyposecretion of other pituitary hormones with impaired responses in their provocative tests and partially empty sella.