There is high incidence of relative adrenal insufficiency (RAI) in critical children. The causes of adrenal insufficiency in patients with severe sepsis and septic shock are the mechanical injury of the hypothalamic-pituitary-adrenal axis, cytokines and other mediators of inflammatory or hormone resistance. There are many symptoms associated with adrenal insufficiency. Diagnosis is often suspected when these patients have hypotension refractory to fluid therapy and to vasoactive drugs. The corticotropin stimulation test is widely used as a method to identify adrenocortical hyporesponsiveness, but controversy exists as to the corticotropin dose to be used. The 250 μg dose is the standard dose. Low doses of corticotropin (1 μg) have recenfly been proposed,suggesting that they may have higher sensitivity and the characteristics of safe and effective.