Objectives : The root of Codonopsis pilosula (Fr.) Nannf. (Codonopsis Pilosulae Radix) has been traditionally used as a oriental medicine with an anti-thrombotic, antidiabetic, anticancer, and anti-gastric ulcer effects and immunological adjuvant. In this study, we investigated the effect of 70% ethanol extract of Codonopsis Pilosulae Radix (CPR-E) on ovalbumin (OVA)-induced allergic responses in mice. Methods : Mice were sensitized (1, 8, and 15 days) with OVA and airway challenged(22, 24, 26, 28, and 30 days) to induced allergic responses. CPR-E extract at doses of 50 and 100 mg/kg/body weight was orally administered from days 21 to 30 consecutively. The levels of allergic mediators such as histamine, OVA-specific immunoglobulin (Ig) E, and Th1/Th2 cytokines such as IFN-${gamma}$ and IL-4 were measured in the sera of mice by ELISA. The histological change of lung tissue was observed by hematoxylin and eosin (H&E) staining. Results : CPR-E extract significantly decreased the serum levels of histamine, OVA-specific IgE, and IL-4 compared with those of OVA control group, but significantly increased the serum level of IFN-${gamma}$. Based on H&E staining, CPR-E extract inhibited the infiltration of inflammatory cells into lung tissues with histological changes. Conclusions : These results indicate that CPR-E extract has anti-inflammatory and anti-allergic responses through regulating the cytokine balance, suggesting that the extract may be useful for the treatment of allergic inflammatory diseases such as bronchial asthma and allergic rhinitis.