Fibromyalgia syndrome (FMS) is characterized by systemic pain of unknown etiology and is often accompanied by various psychological symptoms. Research on different parameters in fibromyalgia (FM) indicates that multifactors are involved in its pathophysiology; such as genetic factors, substance P, serotonin, hypothalamic pituitary adrenal axis (HPA), muscles metabolic dysfunction, reactive oxygen species (ROS) and reactive nitrogen species (RNS). Oxidative stress has also been implicated in the pathophysiology of FM; therefore, supplementation with antioxidants may be important in modulation of the effects of ROS in patients with FM.