Objectives : The present study was carried out to investigate the effect of Herba Polygalae Japonica 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 dessiciated with collagenase (1 ${mu}g$/ml). Eosinophils were activated by rIL-3/rmIL-5 co-treatments. The lung cells were treated with extract of Herba Polygalae Japonica (EPJ), incubated for 48 hr at $37^{circ}C$, and analyzed by flow cytometer, ELISA, RT-PCR and immunocytochemistry stain. Results : A significant cytotoxicity by drug treatment was not observed. The cell number ratio of granulocyte, CD3e-/CCR3+, CD3e+CD69+, CD4+, CD23+/B220+ cells was increased in rmIL-5/rIL-3 treated control group compared to the normal group. Cells numbers in the experimental animal group treated with EPJ was all decreased. In ELISA analysis, IL-4, IL-5, IL-13 levels and histamine release level were increased in the control group compared to the normal animal group, then significantly decreased in the experimental group with 100 ${mu}g$/ml of EPJ treatment. In RT-PCR analysis, mRNA expressions of IL-4, IL-5, IL-13, CCR3 and eotaxin were increased in the control group compared to the normal animal group, then decreased in the experimental group with 100 ${mu}g$/ml of EPJ treatment. And eosinophil proliferation levels were 18847${pm}$,1527 (cpm) in the control group, 4676${pm}$972 (cpm) in the positive control group, and 7709 ${pm}$ 549 (cpm), 16839 ${pm}$ 1403 (cpm), 16385 ${pm}$ 1723 (cpm) in the experimental group with 100 ${mu}g$/ml, 10 ${mu}g$/ml, 1 ${mu}g$/ml of EPJ treatment. Conclusions : The present data suggested that Herba polygalae japonica may have an effects on the inhibition of parameters associated with asthma responses in eosinpophils, and thus implicate the possibility for the clinical application of EPJ.