Recent information intensely suggests that eosinophils are pivotal proinflammatory cells in a variety of allergic inflammatory diseases including bronchial asthma, nasal allergy, hypereosinophilic syndrome, and various cutaneous diseases. Eosinophils, via their release of basic proteins and lipid mediators, are strongly implicated in the onset of allergic symptoms of the nose. They play an important role particularly in nasal swelling and hyperreactivity. Despite the current multitude of research investigating eosinophils in vitro, the mechanism that mediates and controls the accumulation of eosinophils in vivo is incompletely understood. In this article the following issues will be addressed: (1) How do eosinophils migrate into the nasal mucosa? (2) What factors contribute to preferential eosinophil accumulation and their degranulation in nasal mucosa? (3) How can we inhibit the eosinophil accumulation and activation?