BACKGROUND: Infiltration of eosinophils in the nasal mucosa is a consistent feature of nasal allergic inflammation. Various cytokines, especially interleukin-5(IL-5), were identified to play important roles in the infiltration and activation of eosinophils in nasal mucosa. Our previous study found that among 4 kinds of sophoricosides extracted from Sophora japonica, named sophi, orobol, genistin, and genistein, 3 compounds except genistein known as protein tyrosine kinase(PTK) inhibitor had anti-inflammatory and anti-IL-5 effects, and sophi was the most potent. OBJECTIVE: The goal of this study was to investigate the antagonism of sophi on the nasal eosinophilia in ovalbumin(OA)-sensitized murine nasal allergy model. METHODS: Male BALB/c mice sensitized intraperitoneally and then topically with OA were treated with sophi(10 or 30mg/kg) or anti-mouse IL-5 monoclonal antibody(anti-IL-5 mAb, 1mg/Kg) intravenously 1 hour before challenge. The effect of sophi on the infiltration of eosinophils into the nasal mucosa, peripheral blood eosinophilia, nasal symptom, and OA-specific IgE antibody production were evaluated. Results: Administration of sophi(10, 30mg/kg) significantly inhibited the nasal eosinophil infiltration and nasal symptom compared to that of anti-IL-5 mAb. But eosinophil count inthe peripheral blood and the titer of OA-specific IgE were not affected by sophi. CONCLUSION: Sophi inhibited not only the tissue eosinophilia but also the acute nasal allergic symptom. These findings suggest that sophi has anti-eosinophilic cytokine activity and also plays blockade of early allergic reaction. Taken together, sophi may be a candidate for new anti-allergic medicine.