Studies suggest that oats can be tolerated in the gluten-free diet by a majority of patients with coeliac disease. Concerns remain, however, about the possibility of contamination of commercially available oat products by wheat, barley and rye. The R5 ELISA allows the identification and quantification of wheat, barley and rye prolamins, and has demonstrated significant contamination in a range of products. If patients with coeliac disease are to take oats, it is important that those consumed are free of contamination. This assay should allow the identification of safe oat products.