There are detailed descriptions of the clinical experiences and prescriptions of asthma in traditional Korean medicine. Zedoariae rhizoma is one of the Korean herbal medicines used to treat bronchial asthma and allergic rhinitis for centuries. However, the therapeutic mechanisms of this medication are still far from clear, In this study, a house-dust-mite (Dermatophagoides pteronyssinus [Der p])-sensitized murine model of asthma was used to evaluate the immunomodulatory effect of Zedoariae rhizoma on the allergen-induced airway inflammation in asthma. Three different protocols were designed to evaluate the treatment and/or long-term prophylacitic effect of Zedoariae rhizoma in Der p-sensitized mice. Cellular infiltration and T-cell subsets in the bronchoalveolar lavage fluid (BALF)of allergen-challenged mice were analyzed. Intrapulmonary lymphocytes were also isolated to evaluate their response to allergen stimulation. When Zedoariae rhizoma was administered to the sensitized mice before AC (groups A and C), it suppressed airway inflammation by decreasing the number of total cells and eosinophil infiltration in the BALF, and downregulated the allergen- or mitogen-induced intrapulmonary lymphocyte response of sensitized mice as compared to those of controls. This immunomodulatory effect of Zedoariae rhizoma may be exerted through the regulation of T-cell subsets by elevation or activation of the CD8+ and double-negative T-cell population in the lung. However, the administration of Zedoariae rhizoma to sensitized mice 24 h after AC (group B) did not have the same inhibitory effect on the airway inflammation as Zedoariae rhizoma given before AC. Thus, the administration of Zedoariae rhizoma before AC has the immunomodulatory effect of reducing bronchial inflammation in the allergen-sensitized mice. On the other hand, to determine the potentiality of prophylactic and/or therapeutic approaches using a traditional herbal medicine, Zedoariae rhizoma, for the control of allergic disease, we examined the effects of oral administration of Zedoariae rhizoma on a murine model of asthma allergic responses. When oral administration of Zedoariae rhizoma was begun at the induction phase immediately after OVA sensitization, eosinophilia and Th2-type cytokine production in the airway were reduced in OVA-sensitized mice following OVA inhalation. These results suggest that the oral administration of Zedoariae rhizoma dichotomously modulates allergic inflammation in murine model for asthma, thus offering a different approach for the treatment of allergic disorders.