A number of chronic inflammatory diseases are associated with IgE-mediated immunologic hypersensitivity, including atopic dermatitis, chronic rhinosinusitis, and asthma. Pathogenetic studies of well characterized patient groups has allowed investigators to more precisely define the molecular pathways involved in these diseases. Specific cytokines and chemokines, as well as other unique proteins, have now been identified in each of these common disorders and a number of medications are currently in development for inhibiting their actions. Continual refinement of our understanding of the pathogenesis of these diseases will undoubtedly yield increasingly precise, and potentially more effective, treatments.