A gluten-free diet is the cornerstone treatment of coeliac disease. Until now, it is not known conclusively whether trace amounts of gluten might be allowed in the diet, as suggested by Codex Alimentarius. Gluten-free foods intended for dietary use can now be analysed reliably for residual gluten by the new R5 enzyme-linked immunosorbent assay (ELISA) system. Some major problems of gluten analysis (sensitivity, specificity, reproducibility) can be solved by the new method. Therefore, the information given by the new test system is relevant and superior to earlier methods. Further clinical studies using small dose challenges and dietary records including gluten analysis are necessary until a more meaningful discussion on standards for gluten-free foods can be started.