BACKGROUND: Fibromyalgia is a chronic musculoskeletal pain syndrome characterized by a broad spectrum of manifestations. Patients with fibromyalgia frequently suffer from manifestations similar to those experienced by patients with gluten-related disorders raising the possibility that some patients with fibromyalgia could suffer from underlying gluten sensitivity. OBJECTIVE: This study aims to assess whether avoiding gluten among patients with fibromyalgia and gluten sensitivity is beneficial. METHODS: Adult patients with fibromyalgia presenting gluten sensitivity symptoms are randomly allocated to receive gluten-free diet or hypocaloric diet for 24 weeks. The primary outcome measure is the mean change in the number of experienced gluten sensitivity symptoms. Secondary outcome measures include the mean changes in the body mass index, Revised Fibromyalgia Impact Questionnaire, Pittsburgh Sleep Quality Index, Brief Pain Inventory, Beck Depression Inventory-II, State-Trait Anxiety Inventory, Short-Form Health Survey and Patient Global Impression Scale of Severity. Other secondary outcome measures include the frequency of potential adverse events and the proportion of responders according to the Patient Global Impression Scale of Improvement. DISCUSSION: Previous studies assessing dietary interventions in fibromyalgia primarily evaluated their effects on the severity and impact of fibromyalgia symptoms and pain. The current study is the first to evaluate the effects of gluten-free diet on the gluten sensitivity symptoms experienced by patients with fibromyalgia. The results of this study will contribute to a better understanding of the potential role of gluten sensitivity in fibromyalgia.