 Fibromyalgia syndrome FMS is a disabling condition mainly characterized by chronic widespread pain, disturbed sleep, fatigue, and distress. The estimated overall prevalence of FMS in Europe is 2.9 and it incurs in high personal, social and healthcare costs. Available treatments in FMS are not curative and there is some evidence of positive effects of mindfulness-based stress reduction MBSR in patients with chronic pain and FMS. Nevertheless, although promising, the positive findings obtained in previous studies implementing mindfulness-based interventions in patients with FMS have to be interpreted with caution due to important methodological limitations e.g. absence of randomization, high attrition rates, or small sample sizes. Therefore, further research in larger studies using more adequate methodologies is warranted. Furthermore, little is known about putative neurobiological processes underpinning the effects of mindfulness training in patients with chronic pain. 