Atopic dermitiis(AD) is a chronic inflammatory skin disease, which requires safe and effective medicinal therapy. Over production of Th2 cytokines and chemokines as well as IgE, which are mediated by highly activated immune cells, have been considered as pathologic factors in this disease. We found that Gamipaidok-san(GPDS), which is a traditional herbal medicine clinically prescribing for atopic dermitis patients in the hospital, has suppressive effects on the development of DNC8 induced dermatitis in Nc/Nga atopic model. Oral administration of GPDS at the concentration of 250 mg/Kg for 12 weeks significantly suppressed the clinical severity of the dermatitis including pruities, edema, eczematous and dryness. Histological examination revealed that thickness of dermis and epidermis were considerably reduced, and the number of infiltrated inflammatory immune cells including mast cells, CCR3+, and CD4+ T cells were decreased in the affected skin and ear, and consistantly, the number of CD3+/CCR3+ cells in Iymph nodes were decreased. The levels of Th2 cytokines produced by activated splenocyte from atopic mice were also down-regulated by GPDS. Furthermore, the serum levels of IgE were considerably reduced, which accompanied by a decrease in the number of B220+IgE+ B cells in the Iymph nodes. Taken together, these results suggested that oral administration of GPDS, a traditional herbal medicine, has suppressive effects on atopic dermitis of Nc/Nga mouse by the modulation of the immune system, therefore GPDS has potential as a natural therapeutic for treatment of atopic dermatitis.