Inflammatory pain is as much a problem in infants and children as it is in adults, whether it arises from medical, surgical or everyday situations. Juvenile rheumatoid arthritis is one of the most common chronic illnesses of childhood with an incidence of 9.2–13.9 cases per 100 000 children in the USA, with peak age of onset of 1–3 years. Patients commonly have morning stiffness, pain after inactivity and nocturnal pain. Younger children show increased irritability, anorexia, guarding of joints and refusal to walk or crawl [108]. Of particular importance is the finding that the existence of background pain in these children influences their acute pain experience and they have been shown to have significantly lower pain thresholds than do their healthy peers, in- dependent of a variety of psychological factors [107]. Postoperative pain is also a major problem for infants and children. The traditional view that neonates cannot feel pain and therefore do not require analgesia has now been totally discredited [96]. There are problems associated with the as- sessment of surgical and procedural pain in preverbal children but where other pain indices, such as body activity, facial expression, autonomic changes and levels of stress hormones, have been carefully monitored, the case is clear cut [95]. Circumcision, for example, which is still routine in 80 % of male infants in the USA causes considerable postoperative pain and distress that lasts for at least several days ([115] and See McGrath and Unruh [77] for review). In our own study we have used the sensory threshold for the flexion withdrawal reflex as a measure of inflammatory pain or hyperalgesia fol- lowing repeated heel lancing in preterm and term infants in intensive care [44]. In these infants the cutaneous flexor reflex threshold in an area of local tissue damage created by repeated heel lances is half the value of that on the intact contralateral heel [41] and this “tenderness” is established for days and weeks in the pr`esence of tissue damage [42]. Furthermore there is evidence that very young infants undergoing intensive care and therefore subject to considerable local inflammatory stimuli have particularly low sensory thresholds [4]. Peripheral tissue inflammation in newborn infants therefore results in a fall in the flexor reflex threshold parallel with that seen in adult animal models [116]