The fruit of Actinidia arguta (AA) has been used mainly for the treatment of skin diseases, diuresis, diabetes mellitus and osteoporosis in Korean traditional medicine. It is known that AA (hardy kiwi) fruit extract has an effect on 2-chloro-1,3,5-trinitrobenzene-induced atopic dermatitis-like skin lesions in NC/Nga mice. Mode of action for it is associated with the modulation of biphasic Th1/Th2 cytokines. Furthermore, DA9102 containing AA is a herbal medicine currently under phase II clinical trial for atopic dermatitis in Korea. However, no active principles of AA on the decrease of Th2 cytokines including IL-4 and IL-10 have been identified. In this study, bioactivity-guided fractionation of an alcohol extract from the dried fruits of AA using ELISA assay for IL-4 production led to the isolation of $alpha$-linolenic acid (I), linoleic acid (II), ethyl linolenate (III), ethyl linoleate (IV) and ethyl stearate (V) as the major active components. These compounds showed the down-regulatory effects of IL-4 production in A23187-stimulated RBL-2H3 cells without cytotoxicity.