At an incidence of 1:500, celiac disease (formerly sprue) is an important di erential diagnosis in patients with malabsorption, abdominal discomfort, diarrhea and food intolerances. Celiac disease can
induce a broad spectrum of both gastrointestinal and extraintestinal symptoms, e.g. dermatitis herpetiformis (Duhring’s disease). A variety of oligoand asymptomatic courses (e.g. anemia, osteoporosis, depression) through to refractory collagenic celiac disease are seen. In HLA-DQ2 and -8 predisposed individuals, celiac disease is provoked by contact with wheat gliadin fractions through a predominantly  1 immune response and an accompanying  2 response, which can eventually lead to villous atrophy. Using appropriate serological tests (IgA antibodies against tissue-transglutaminase, endomysium and deamidated gliadin peptides) under su cient gluten ingestion, the diagnosis can be made more reliably today than previously.  e same IgG-based serological tests should be used in the case of IgA de ciency. Diagnosis can either be made in children and adolescents with anti transglutaminase titers exceeding ten times the standard for two of the abovementioned serological markers and HLA conformity or it is made by endoscopy and histological Marsh classi cation in adults and in cases of inconclusive serology. If clinically tolerated, gluten challenges are indicated in patients that already have reduced gluten intake, in borderline serological results, discordance between serological and histological results or in suspected food allergy.  e diagnosis of celiac disease needs to be de nitive and robust before establishing a gluten-free diet, since lifelong abstention from gluten (gliadin < 20 mg/kg foodstu s), cereal products (wheat, rye, barley and spelt) as well as from preparations and beverages containing gluten, is necessary. With e ective elimination of gluten, the prognosis regarding complete resolution of small bowel in ammation is good. Refractory courses are seen only in rare cases, accompanied by enteropathy-associated T-cell lymphoma.