Objectives : The purpose of this study was to investigate the effects of Polygonum tinctoria Niram(PTN) on atopic dermatitis(AD) in hairless mice induced by 2,4-dinitrochlorobenzene(DNCB). Method : They were divided into four group, Nor, Con, 1X and 5X, for evaluating the change of appearance of skin surface, skin hydration, thickness of epidermis and mast cell numbers during 30 days. Results : PTN suppressed symptoms of AD in appearance of skin and increased skin hydration for 1X and 5X. In histopathological examination, 1X and 5X significantly reduced the thickness of epidermis and number of mast cell in dermis. These results suggested that the PTN improved the AD-like symptoms of hairless Mice.