Articular involvement is the most frequent extra-intestinal manifestation of inflammatory bowel diseases (IBD). IBD-related spondyloarthropathy is mainly characterised by axial involvement (including inflammatory back pain, isolated sacroiliitis and ankylosing spondylitis) but may also be associated with peripheral symptoms (i.e peripheral arthritis, dactylitis and enthesopathy, such as Achilles tendinitis, plantar fasciitis, and chest wall pain). In particular, inflammatory back pain (IBP) is characterised by an insidious onset, improves after exercise but not with rest, and is associated with morning stiffness. Up to now, several criteria sets have been proposed to define IBP. Studies conducted in various populations have confirmed a high sensitivity and specificity for the Berlin criteria. Celiac disease (CD) is an autoimmune systemic disease having among its clinical manifestations frequent symptoms common to rheumatologic diseases. Recently, it has been reported that a consistent percentage of the general population consider themselves to be suffering from problems caused by wheat and/or gluten ingestion, even though they do not have CD or wheat allergy. This clinical condition has been named Non-Celiac Gluten Sensitivity' (NCGS) or Non-celic Wheat Sensitivity (NCWS). The clinical picture of NCWS is characterized by combined gastrointestinal and extra-intestinal or systemic manifestations. Many patients affected with CD and NCWS complain of IBP-like symptoms, which generally improve, together with the other clinical manifestations of the diseases, during a gluten-free diet (GFD). Therefore, the aims of the present study are to investigate 1) the effect of a GFD in IBP patients, randomly assigned to receive standard therapy for IBP or standard therapy for IBP plus GFD, for a period of at least one year, and 2) the prevalence of IBP in CD and in NCWS patients.