Coeliac disease (CD) is caused by a complex immunological response provoked by grain protein in susceptible people. The majority of people with CD are symptom-free adults; the remainder are prone to a bewildering variety of signs and symptoms, ranging from infertility to type 1 diabetes. Many patients with undiagnosed CD spend years seeking help for complaints such as chronic tiredness or mild abdominal symptoms. In primary care, an appropriate target group to test for CD is people with anaemia (especially women), chronic tiredness, non-specific abdominal symptoms (including so-called "irritable bowel syndrome"), or a family history of CD. The response to an appropriate gluten-free diet is often life-transforming for symptomatic patients. Positive serological tests for CD require confirmation by duodenal biopsy and, if confirmed, referral to a dietitian and a coeliac society, followed by a life-long gluten-free diet.