Fibromyalgia syndrome (FMS) can be conceptualized as a chronic disorder characterized by widespread musculoskeletal pain and other accompanying symptoms such as fatigue, insomnia, depression, anxiety and cognitive impairments. The etiology of FMS remains unknown, being one of the most accepted hypothesis the presence of central sensitization to pain and impairments in endogenous pain inhibitory mechanisms. The history of the development of FMS concept reveals how other symptoms -apart from

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... has become also relevant in FMS diagnosis and treatment. The central symptom of FMS is pain. FMS patients generally report high levels of clinical pain, which are related to greater impairments in health related quality of life, cognitive abilities and disease course. Fatigue and sleeping difficulties are also common symptoms of FMS. Fatigue have shown positive associations with pain, stiffness, sleep problems, increased body mass index, FMS severity, tenderness, disability, cognitive complaints, anxiety and depression. The majority of FMS patients report poor sleep quality, take longer to fall asleep, generally wake up during the night, sleep fewer hours, and usually wake up unrefreshed. Emotional disturbances (i.e., depression, anxiety) are also frequent in FMS. In fact, depression and anxiety disorders have showed a negative impact on the clinical course and work capacity of FMS patients. Cognitive impairments are also a relevant symptom in FMS. The most common complaints among FMS patients are executive function deficits, attention problems, forgetfulness, concentration difficulties, and mental slowness. Regarding the most frequent treatments for FMS, these can be classified as non-psychological and psychological. The former includes analgesic drugs, adjuvant drugs (i.e., antidepressants, benzodiazepines, anticonvulsants, etc.), nerve blocks, electrostimulation at different levels, infiltrations, etc. The psychological therapies with the most evidence are cognitive-behavioral, acceptance and commitment therapy and mindfulness. FMS is associated with a severe reduction of health related quality of life and psychosocial impairments. It is necessary to take all FMS symptoms and its relations into account in order to provide a more tailored and effective treatment, as well as, to improve the health related quality of life of FMS patients.