Complex regional pain syndrome (CRPS) is divided into two types. Type I occurs without obvious nerve injury. In type II, a peripheral nerve injury is present, although pain may not be limited to the distribution of that nerve. Diagnosis rests on the presence of a constellation of symptoms and signs. These include extreme sensitivity, changing skin colour and temperature, trophic changes in the skin, nails and hair, reduced range of motion and loss of function. These features are accompanied by considerable pain for which no other unifying diagnosis can be made. CRPS typically starts with an injury to an extremity which is often seemingly trivial, followed by immobilisation, such as an ankle sprain or Colles' fracture. Instead of the expected resolution of symptoms, persistent pain and dysfunction develop. CRPS usually has an early warm phase that suggests an inflammatory process, with local swelling, erythema and heat. It then progresses to a cold phase, which often goes on for months or years. It is important to keep the affected part moving as much as possible, especially in the early stages. Sensory stimulation, particularly by self-massage, is advised. Aggressive treatment in the early stages improves prognosis. Many cases, especially those with relatively minor symptoms, will resolve spontaneously. Patients who are symptomatically deteriorating, despite regular analgesia, neuropathic agents and physiotherapy, should be referred to a specialist.