Abstract: Fibromyalgia (FM) is one of the most common causes of chronic widespread pain. With the pain being its main and distinguishing feature, FM is characterized by a complex polysymptomatology that also comprises fatigue, sleep disturbances and functional symptoms. FM is the third most common musculoskeletal condition in terms of prevalence, ranks after lumbar pain and osteoarthritis. Although its etiopathogenesis has not been defined clearly, FM is recognized as a result of interactions between neurophysiological factors (neuroplasticity) and socio-environmental stressors. Given the low awareness of FM, it has been underdiagnosed, overdiagnosed and misdiagnosed in a number of cases. It is very important to understand the clinical features, diagnostic criteria, common misdiagnosed diseases and other concomitant diseases with FM, which is essential to improve the ability of clinicians to identify FM.