Non-celiac gluten/wheat sensitivity (NCGS/NCWS) is a syndrome characterized by both intestinal (irritable bowel syndrome \[IBS\]-like presentation) and extraintestinal symptoms (headache, migraine, foggy mind, depression, anxiety, fibromyalgia, joint and muscle pain, leg or arm numbness, eczema or skin rash), which occur after the ingestion of gluten/wheat in subjects in which celiac disease (CD) and wheat allergy diagnosis has been previously excluded. NCGS/NCWS symptoms generally occur after the ingestion of gluten/wheat, disappear within a few days of a gluten-free diet (GFD) and quickly reappear when gluten/wheat is reintroduced. A new assay, recently available on the Italian market, allows to ascertain the presence of immunogenic peptides of gluten (Gluten Immunogenic Peptides, GIP) in the urine and stool. The test might allow to ascertain if the NCGS/NCWS patients, on GFD, eat, even accidentally, gluten. Of the 2 available assays, the urinary one allows the patient himself to test the presence of GIP in relation to symptoms/signs appearing and/or social activities (e.g. meal in a restaurant). The aims of the present study are: 1) to test, in patients with NCGS/NCWS on GFD, the adherence to the elimination diet; 2) to evaluate the correlation between the symptoms' reappearance and the presence of GIP in the urine.