Objectives : The present study was carried out to investigate the effect of Trichosanthis Radix extract (TRE) on the proliferation and activation of eosinophils which were prepared from lung cells of asthma-induced mice by ovalbumin (OVA) treatment. Methods : C57BL/6 mouse was exposed to OVA three times a week for 6 weeks. The mouse lung tissues were dissected out, chopped and dossiciated with collagenase (1 $mu$g/ml). Eosinophils were activated by rmIL-3/rmIL-5 co-treatments. The lung cells were treated with TRE, incubated for 48 hr at 37$^{circ}C$, and analyzed by flow cytometer, ELISA and RT-PCR methods Results : To measure cytotoxicity, mouse lung fibroblast cells (mLFCs) were pretreated with various concentrations of TRE. TRE at 100 $mu$g/ml, the highest concentration, examined did not have any cytotoxic effects on mLFCs. In FACS analysis, number of granulocyte/lymphocyte, CD3e-/CCR3+, CD3e+/CD69+, CD4+/CD8+ T cells in asthma-induced lung cells were significantly decreased by TRE treatment compared to the control group. But CD4+/CD25+ T cells were not examined significant change in lung cells treated with TRE. In ELISA analysis, production levels of IL-3, IL-5, IL-13 and histamine in asthma-induced lung cells, which were induced by rIL-3 plus rmIL-5 co-treatment, were significantly decreased by TRE treatment. Conclusions : The present data suggested that Trichosanthis Radix on the inhibition of parameters associated with asthma responses in eosinpophils, and thus implicate the possibility for the clinical application of Trichosanthis Radix.