Therapy options for allergies are increasing in number. Various therapeutic allergen products are available for allergic patients, but there is a lack of standard methods for comparing the active ingredient content of the available products. In an international ring trial coordinated by the Paul-Ehrlich-Institut, a test method (ELISA) was trialled for the allergen Phl p 5 in timothy grass pollen, to which up to a quarter of the European population is sensitized. In all the participating laboratories, the method successfully quantified the allergen. The results are reported in Allergy in its online edition dated 9 July 2021.