The metabolic and endocrine response to surgery has been investigated in detail for many years. The current view is that the response is detrimental to the patient and that the prevention or reduction of the changes may be beneficial in aiding recovery from surgery. Three main methods are available at present for modifying the response. First, the use of afferent neuronal blockage, by epidural or spinal analgesia, to inhibit the transmission of impulses from the site of trauma. Secondly, the intravenous administration of large doses of potent opiate analgesics to block hypothalamic-pituitary function. Thirdly, the hormonal status of the patient may be changed, either by the use of agents to inhibit the secretion or action of the catabolic hormones, or by the infusion of anabolic hormones such as insulin.