Abstract Public anxiety over gluten has fuelled widespread demand for gluten-free food, yet coeliac disease remains significantly underdiagnosed and some confusion remains regarding optimal diagnostic practices. Small bowel histology is the gold standard for diagnosis. High-quality commercial enzyme-linked immunosorbent assays for transglutaminase immunoglobulin A and deamidated gliadin immunoglobulin A and G are sensitive tools for screening, but almost 10% of coeliac disease is seronegative and serological testing is unreliable in the very young, in people already following a gluten-reduced diet, and those using immunosuppressive medications. HLA DQA and DQB genotyping to show that alleles encoding HLA DQ2 and DQ8 are absent virtually excludes coeliac disease. Confirming histological remission reduces the risks of later complications, such as osteoporosis and cancer. Monitoring remission by serology is unreliable. Because gluten is an exogenous antigen and the small intestine is readily accessible, the immunopathogenesis of coeliac disease is better understood than other strongly major histocompatibility complex class II-associated diseases, such as type 1 diabetes mellitus. Therapeutic targets have been identified and drugs are under development to supplement or even replace gluten-free diet. With greater awareness and non-dietary therapeutics, diagnosis and treatment of coeliac disease will be increasingly prominent in medical practice.