The effects of SUN13834, an oral chymase inhibitor, on pruritus were evaluated in a 5-week atopic dermatitis mouse model induced by repeated topical application of 2,4-dinitrofluorobenzene (DNFB). The administration of SUN13834 for 5 weeks was found to inhibit skin swelling and the accumulation of inflammatory cells such as mast cells and eosinophils, and to significantly reduce the scratching behavior at 10 and 50 mg/kg. These findings suggest that SUN13834 may be an effective therapeutic option in atopic dermatitis (Terakawa, M. et. al. Eur J Pharamcol 2008, 601: 186).