Reflex sympathetic dystrophy presents with pain out of proportion to the cause, loss of function, and significant evidence of an autonomic disorder. These findings are often accompanied by psychological disturbances, which can dominate the condition. There are differences in the symptoms and signs during childhood. It is more frequent among girls than boys, and the legs are more often affected than the arms; and trophic changes may be absent. There may be no history of trauma, and the response to treatment is often satisfactory. There are a number of theories on etiology. A disorder of the sympathetic nervous system with increased activity has been suggested, but on the evidence available super-sensitivity to neurotransmitters is more likely. Also there may be a spinal, as well as a peripheral, component to the sensitivity. Other suggestions include the release of a pain substance, a disturbance of natural opioid metabolism, and an exaggerated inflammatory response. The diagnosis is mainly clinical, supported by X-ray examination, bone scans with Technetium 99m labelled diphosphonates, and a characteristic scintograph pattern. Laser Doppler flowmetry can also, be useful. The most effective preventative measure is control of pain and early mobilisation. Many treatments have been tried, but the response is variable. Drugs include analgesics, non-steroid anti-inflammatory drugs, anti-depressants, and steroids. Betablockers, with gradually increasing doses may help; as may vasodilators. Calcitonin, by intramuscular injection has been given a particularly favourable report. Physiotherapy is of prime importance. Some treatments are only likely to be considered in older children. Blocking of sympathetic pathways can be tried with paravertebral or epidural injections of local anesthetics. Regional intravenous injections of alpha adrenergic blocking agents distal to a tourniquet can relieve pain, but usually only transiently; and ketanserin may act favourably as a serotonin antagonist. Surgical sympathectomy can also be considered.