Equisetum hyemale Linne. (EH) (Equisetaceae) has been used for the treatment of eye and skin disease, chronic eczema, pneumoconiosis and asthma in Korea and China. Human leukemic mast cells are widely distributed in the connective tissues of mammals and other vertebrates. Phorbol 12-myristrate 13-acetate (PMA) and calcium ionophore A23187 stimulated Human leukaemic mast cell line-1 (HMC-1) can produce a variety of inflammatory mediators and several pro-inflammatory and chemotactic cytokines such as TNF-$alpha$, IL-6 and IL-8. Since TNF-$alpha$, IL-6 and IL-8 are major factors during the inflammatory process, we studied the effects of EH on TNF-$alpha$, IL-6 and IL-8 release in HMC-1 stimulated with PMA and A23187. The result of this study indicate that EH inhibits TNF-$alpha$, IL-6 and IL-8 in activated HMC-1 cells via $I{kappa}B$/Nuclear factor-${kappa}B$ pathway. Therefore, EH might contribute significantly to the prevention or treatment of mast-cell mediated inflammatory diseases and EH has potential use in the therapy of chronic allergic inflammation.