Fibromyalgia syndrome (FMS) is characterised by diffuse muscle pain, poor sleep and unrelenting fatigue. Individuals with FMS may also experience headaches, anxiety, depression, poor memory, numbness and tingling in the extremities, cold hands and feet, irritable bowel syndrome and lowered immune function. FMS is a common chronic pain syndrome of unknown etiology and limited treatment options. Previous studies have reported oxidative stress in FMS patients, but the results were inconsistent. Oxidative stress and nitric oxide is involved in FMS pathophysiology, however, it is still not clear whether oxidative stress abnormalities are the cause of FMS. There are several studies indicating oxidative stress in patients with FMS. Oxidant (Malondialdehyde) and antioxidant (Superoxide dismutase) balances were found to be changed in FMS patients. Furthermore, increased free radical levels may be responsible for the development of FMS and free radical-mediated oxidative stress including inflammatory cytokines may also play important roles in its pathogenesis. Moreover, oxidative stress is supposed to be increased in patients with FMS which is related to the severity of FMS symptoms. Therefore, it is important to understand whether the oxidative stress parameters are involved in FMS and what is the relationship between these and antioxidants in FMS patients. In this review we will elucidate the importance of oxidative stress and antioxidants and its possible relationship with FMS. Moreover, as metal toxicity is also reported to be involved in the pathogenesis of FMS, therefore we will also try to establish the role of toxic metals in the pathogenesis of FMS.