Dendritic cells are crucial in determining the functional outcome of allergen encounter in the lung. Antigen presentation by myeloid DCs leads to Th2 sensitization typical of allergic disease, whereas antigen presentation by plasmacytoid DCs serves to dampen inflammation. It is increasingly clear that DCs have an antigen presenting function beyond sensitisation. DCs therefore constitute a novel target for the development of anti-allergic therapy aimed at the origin of the inflammatory cascade. A careful study of DC biology and of the receptors expressed by lung DCs has provided a framework for the discovery of novel anti-allergic compounds.