Objective:To investigate the role of ORMDL3 in development of bronchial asthma and its response to treatment with dexamethasone. Methods:A total of 30 Balb/c female mice were randomly divided into three groups: control group,untreated asthma group,and dexamethasone-treated group,and 10 mice in each group. The body weight was observed every week and HE-stained was used to observe the changes of pulmonary histopathology. The number of eosnophils(EOS) in peripheral blood of three groups was counted under microscope. The concentration of interlukin-4 (IL-4) was determined by ELISA and the expression of ORMDL3 mRNA in lungs was detected by semi-quantitative RT-PCR. Results:Weight gain of asthma group was significantly lower than the other two groups (P < 0.05),and dexamethasone intervention alleviated the physical retardation,but still lower than the control group (P < 0.05). There were mass inflammatory cells infiltration in asthmatic group. Dexamethasone ameliorated the above mentioned symptoms significantly. The number of EOS which in treated in untreated asthma group were significantly higher than those in the other two groups(P < 0.05), and group were higher than those in control group(P < 0.05). IL-4 was increased after challenged by OVA compared to the control group (P < 0.05),and it was lower after treated by dexamethasone (P < 0.05). After challenge, the expression of ORMDL3 mRNA was a significantly elevated in untreated asthma group,and was alleviated in dexamethasone-treated group(P > 0.05),which was still higher than the control group. Conclusion:Over-expression of ORMDL3 was demonstrated in the mouse airways with asthma,and dexmathesone may be effective as an anti-inflammatory agent by inhibiting ORMDL3 expression.