Coeliac disease is a genetically-determined chronic inflammatory intestinal disease induced by an environmental precipitant, gluten. Patients with the disease might have mainly non-gastrointestinal symptoms, and as a result patients present to various medical practitioners. Epidemiological studies have shown that coeliac disease is very common and affects about one in 250 people. The disease is associated with an increased rate of osteoporosis, infertility, autoimmune diseases, and malignant disease, especially lymphomas. The mechanism of the intestinal immune-mediated response is not completely clear, but involves an HLA-DQ2 or HLA-DQ8 restricted T-cell immune reaction in the lamina propria as well as an immune reaction in the intestinal epithelium. An important component of the disease is the intraepithelial lymphocyte that might become clonally expanded in refractory sprue and enteropathy-associated T-cell lymphoma. Study of the mechanism of the immune response in coeliac disease could provide insight into the mechanism of inflammatory and autoimmune responses and lead to innovations in treatment.