There has been a resurgence in interest in the in-hospital management of pain, largely related to results of investigations into the role of analgesia in outcome and cost-efficiency. The traditional aim of analgesia as simply an altruistic goal has been supplanted by the goal of impacting on the altered physiology accompanying critical illness and trauma. Elucidation of the effect of pain and the accompanying stress response on pulmonary dysfunction in particular, but also on myocardial ischemia and coagulation, has suggested that the provision of adequate analgesia by time-honored methods may not in itself effect a reduction in morbidity without attention to the method of analgesic delivery and choice of agent.