ABSTRACT: Fibromyalgia syndrome (FMS) is a common condition that causes chronic pain and disability. It should be diagnosed by its own clinical characteristics of widespread musculoskeletal pain and multiple tender points. American College of Rheumatology criteria guidelines are most helpful in diagnosing FMS. The major symptoms are pain, stiffness, fatigue, poor sleep, and those of other associated conditions, for example, irritable bowel syndrome, headaches, restless legs syndrome, chronic fatigue syndrome, and depression. The pathophysiology of FMS is thought to involve central sensitization and neuroendocrine aberrations, triggered or aggravated by genetic predisposition; trauma; psychosocial distress; sleep deprivation; and peripheral nociception.