The HUNT Celiac Research Group works with epidemiology, genetics and molecular aspects of coeliac disease. Our research is based on the fourth round of the Trøndelag Health Study (HUNT4), where 56 000 adult participants above 20 years of age participated. Blood samples from these participants where screened for celiac disease by a serological assay developed by our research groups. All seropositive participants were invited to a clinical assessment at Levanger Hospital, Nord-Trøndelag Hospital Trust, including upper gastrointestinal endoscopy with tissue sampling from the small intestine. Furthermore, the participants filled out extensive written questionnaires about their disease specific and general health, delivered blood (serum and plasma), saliva and fecal samples for biobanking, and were assessed by bone density measurements and dental panorama x-rays.