The neuroendocrine response to surgical trauma is a complex set of hormonal and metabolic changes evoked by anxiety, blood loss, tissue damage, visceral handling, and also by the anaesthetic drugs and procedures (Traynor & Hall, 1981). A useful approach to understanding the surgery-induced stress syndrome is to individualize these stressful stimuli in order to explore the specific effects of anxiety, anaesthesia or surgery itself on the endocrine and metabolic responses that are observed altogether. The relative importance of each element contributing to surgical stress should be better characterized in order to provide the rationale for improving the management of surgical patients. For instance, it remains unclear whether the physiological alterations induced by surgical stress are a single syndrome arising from the addition of several stressors or comprise parallel responses to each stressor, with some convergent end-points.