The ability of the somatosensory system to detect noxious and potentially tissue-damaging stimuli is an important protective mechanism, that involves multiple interacting peripheral and central mechanisms. The postoperative pain is related with surgical procedure irrevocable. The effective relief of pain is of paramount importance to anyone treating patients undergoing surgery. This should be achieved for humanitarian reasons, but there is now evidence that pain relief has significant physiological benefit. Not only does effective pain relief mean a smoother postoperative course with earlier discharge from hospital, but it may also reduce the onset of chronic pain syndromes. Pain causes an increase in the sympathetic response of the body with subsequent rises in heart rate, cardiac work and oxygen consumption. Prolonged pain can reduce physical activity and lead to venous stasis and an increased risk of deep vein thrombosis and consequent pulmonary embolism. In addition, there can be widespread effects on gut and urinary tract motility which may lead, in turn, to postoperative ileus, nausea, vomiting and urinary retention. These problems are unpleasant for the patient and may prolong hospital stay. Choice of technique will also be influenced by the degree of training and expertise of the staff. The choice of pain-relieving techniques may be influenced by the site of surgery.