Coeliac disease is a clinical condition characterised by malabsorption secondary to abnormalities of the small intestine. The condition is known to be exacerbated by wheat gliadin, rye, barley and possibly oats. The only assays that are available for testing for the presence of wheat gluten in foods are double diffusion against rabbit anti-gliadin antiserum and measurement of Kjeldahl nitrogen in products derived from wheat flour. We have developed a radioimmunoassay for wheat gliadin with a detection limit of 1 ng. Nominally gluten free foods based on wheat starch have been shown to contain up to 1.9 X 10(-2)% wheat gliadin. Bread made from Nutregen wheat starch which has now been withdrawn contains 6.4 mg gliadin per standard 30 g slice. A radioimmunoassay for wheat gliadin could be used to define standards for the suitability of gluten free products based on wheat starch for patients with coeliac disease.