Allergic diseases are among the most prevalent immune-mediated diseases, with incidences of well over 20% of the population in industrialized countries. Nevertheless, the question of whether allergies should be considered as a risk factor for exposure to nanomaterials has rarely been addressed. Experimental studies have attempted to improve allergy therapy by combining allergens with various nanomaterials, which may lead to a beneficial re-direction of the immune system. Binding to nanoparticles may for allergens – as for other proteins – lead to structural changes or modification of other properties. We assess here the state of knowledge about biological effects deriving from the combination of nanoparticles with allergens.