The human neuroendocrine system has two components, hormonal secretion that is controlled by hypothalamo-pituitary axis and extra-hypothalamic neurohormones. Hypothalamus is responsible for the maintenance of homeostasis and the integration of nervous and endocrine control mechanisms. It regulates many of the body's autonomic functions, such as temperature, thirst and hunger, blood pressure and volume, sleep and sexual function, and is intimately related, both anatomically and functionally, to the pituitary gland. The majority of clinically significant pituitary conditions are the result of tumour or tumour-like conditions that arise from either within the gland itself or in surrounding parasellar tissues. The endocrine hyposecretion syndromes associated with pituitary disease of relevance to perioperative care include adrenocortical insufficiency, hypothyroidism and diabetes insipidus. Sellar or parasellar lesions rarely present with failure of posterior lobe function, although it is a relatively frequent complication of surgical resection.