Cyclic AMP, glucose and cortisol in plasma were measured in three groups of patients undergoing hysterectomy. The operations were performed under general anaesthesia, under general anaesthesia combined with epidural analgesia and under epidural analgesia alone. Surgery elicited a significant rise in plasma cyclic AMP, glucose and cortisol when performed under general anaesthesia alone. Epidural analgesia extending from T4-6 to S5 combined with general anaesthesia abolished the rise in cyclic AMP and reduced the increase in glucose and cortisol and epidural analgesia alone extending from T4 to S5 blocked the rise in glucose and cortisol as well as that in cyclic AMP. The results support the theory that afferent nerve impulses from the area of trauma are of major importance for the catabolic state induced by surgical procedures and indicate that anaesthetic management which includes blockade of afferent nerve impulses which includes blockade of afferent nerve impulses from the area of trauma can be reduce the catabolic response to surgery. These observations could be of value in the operative management of patients with diabetes mellitus and possibly in other groups by patients with a high surgical morbidity.