Fibromyalgia is a functional somatic syndrome characterized by widespread musculoskeletal pain, fatigue, poor sleep, and exercise intolerance, frequently (but inconstantly) associated with psychological distress. Fibromyalgia is a common condition, affecting predominantly middle-aged women, with a chronic course. Fibromaylgia should be differentiated from, and may be associated with, a number of metabolic, rheumatic, neurological or psychiatric conditions. The most plausible pathophysiologic mechanism involves an alteration of pain modulation at the peripheral and central levels of the nervous system ("sensitization"). Psychosocial factors play an important role in precipitating and maintaining symptoms, health care utilization, and disablement. Treatments of fibromyalgia rely mainly on the acknowledgement of pain and distress, patient education, analgesics, balneotherapy and physiotherapy, physical reconditioning (aerobic exercise), and certain antidepressants.