Adrenal insufficiency can be either primitive as the result of a destruction of the glands or secondary to a corticotropic failure. Adrenal insufficiency can appear as an acute event or in contrast arise progressively. An acute adrenal insufficiency can occur any time and threatens the vital prognosis. It should be prevented by adapted treatment and education of the patient. The treatment of adrenal insufficiency includes substitutive doses of mineralo and/or glucocorticoids and, as often as possible, etiologic therapy. For this reason, as soon as the diagnosis of adrenal insufficiency has been done, a main point is to determine the cause of the endocrine failure. Indeed, some diseases responsible for adrenal deficiency, among a progressively extending list of etiologic factors, can benefit for a specific treatment.