Equisetum hyemale Linne. (EH) (Equisetaceae) has been used for the treatment of eye and skindisease, chronic eczema, pneumoconiosis and asthma in Korea and China. Human leukemic mastcells are widely distributed in the connective tissues of mammals and other vertebrates. Phorbol12-myristrate 13-acetate (PMA) and calcium ionophore A23187 stimulated Human leukaemicmast cell line-1 (HMC-1) can produce a variety of inflammatory mediators and several pro-inflammatory and chemotactic cytokines such as TNF-α, IL-6 and IL-8. Since TNF-α, IL-6 and IL-8are major factors during the inflammatory process, we studied the effects of EH on TNF-α, IL-6and IL-8 release in HMC-1 stimulated with PMA and A23187. The result of this study indicatethat EH inhibits TNF-α, IL-6 and IL-8 in activated HMC-1 cells via IκB/Nuclear factor-κBpathway. Therefore, EH might contribute significantly to the prevention or treatment of mast-cellmediated inflammatory diseases and EH has potential use in the therapy of chronic allergicinflammation.