This article is a review of present knowledge of the hormonal and metabolic responses to trauma and surgery. The factors which may mediate the responses are discussed and the potential value of different therapeutic manipulations are reviewed. The accelerated breakdown of muscle following significant injury is the most characteristic feature of the metabolic response. The magnitude of the muscle wasting that is potentially proportional to the extent of injury, leads to a marked cachexia which could be considered a part of the multiple organ failure. It does seem that the protein loss and the immunodepression which often occurs after major trauma may be important factors in determining morbidity and mortality of the patients. The prevention or the attenuation of the metabolic stress response could be beneficial in improving immunocompetence and minimizing complications after major trauma or surgery so that an earlier return to normal health could be achieved. At present there are few epidemiological data to support this view but it is an attractive concept in the management of a severely ill patients. We are aware that anaesthetic techniques, nutritional support, normothermia and hormonal manipulation can modify part of the hormonal and metabolic response to surgery. The knowledge of all of them and the clinical implications that their use could have, will be helpful to the anaesthesiologists and the Intensive Care physicians in their daily working in the operation theatre, intensive care unit or in the surgical ward.