Objectives : The effect of water extract of the pilose antler of Cervus korean TEMMINCK var. mantchuricus Swinhoe (Nokyong), a traditional immuno-suppressive and immuno-activating Korean oriental medicine, on collagen-induced arthritis (CIA) mice model was studied. Identification of common Nokyong capable of affording protection or modulating the onset and severity of arthritis may have important human health implications. Methods : Nokyong has shown to possess anti-inflammatory and anticarcinogenic properties in experimental animals. In this study we determined the effect of DAE on collagen-induced arthritis in mice. Results : In three independent experiments mice given DAE in water exhibited significantly reduced incidence of arthritis (33% to 50%) as compared with mice given no DAE in water (84% to 100%). The arthritis index also was significantly lower in DAE-fed animals. Western blot analysis showed a marked reduction in the expression of inflammatory mediators such as cyclooxygenase 2 (Cox-2), $Interferon-{gamma};(INF-{gamma})$, and tumor necrosis factor ${alpha};(TNF-{alpha})$ in arthritic joints of DAE-fed mice. The neutral endopeptidase (NEP) activity was approximately 6-fold higher in arthritic joints of non-DAE-fed mice in comparison to nonarthritic joints of nonimmunized mice whereas it was only 2-fold higher in the arthritic joints of DAE-fed mice. Additionally, total IgG and type II collagen-specific IgG levels were lower in the arthritic joints of DAE-fed mice. Conclusion : Taken together our studies suggest that DAE may be useful in the prevention of onset and severity of arthritis.