The widespread use of adrenal steroids as therapeutic agents has demonstrated that these hormones, if given long enough in sufficient dosage, consistently induce adrenal atrophy and suppress pituitary and adrenocortical function. Less well known, perhaps, is that adrenocortical and pituitary function may also be impaired for some time after corticotropin has been administered. Changes may persist for as long as six months after therapy has been stopped. Eventually, however, function returns to normal, and the interlude of hormone-induced adrenocortical insufficiency is usually not of serious importance. If an episode of stress should supervene at this time, however, the consequences may be grave. To maintain homeostasis under stress, increased amounts of adrenocortical hormones are needed. A normal adrenal cortex responds with a manifold increase in hormonal output; the adrenal cortex that has been suppressed by prolonged administration of exogenous adrenal hormones cannot always respond adequately. Fraser and others, and Lewis and