Erythromelalgia is the syndrome or group of symptoms characterized by intense burning pain and raised temperature of the affected part (usually the lower limbs), and associated with redness of the skin. It occurs in both a primary and a secondary form and treatment can be difficult. The key to understanding this disorder is in the careful evaluation of the patient, both in the clinic and in the laboratory. Both forms of erythromelalgia are discussed in this review, as are suggestions for evaluation and management of the patient.