In Europe, one-third of desensitization treatments for grass pollen allergy are supplemented with a mixture of cereal pollen extracts (Triticum sativum, Avena sativa, Zea mais and Hordeum vulgare). We have re-evaluated this practice in light of the recent availability of a desensitization tablet prepared from a mixture of pollen from five common grass species (Anthoxanthum odoratum, Dactylis glomerata, Lolium perenne, Poa pratensis and Phleum pratense) from the Pooideae subfamily. Common grasses and cultivated cereals are very closely related phylogenetically, and as a consequence, their pollen exhibit a similar molecular composition. The latter is confirmed by ELISA inhibition and immunobloting experiments. Thus, immunotherapy based on a mixture of five grass pollen allows to treat patients sensitized with pollen allergens from cultivated cereals, without a need for additional cereal pollen extracts.