Objective:To investigate the changes of T helper 17 cells and the level of IL-17 in bronchial asthmatic mice. Methods:Twenty-four BABL/c mice were randomly divided into two groups,asthma group and control group. The asthmatic mouse models were established after ovalbumin(OVA) sensitization and challenge. The airway inflammation of lung tissue was observed by hematoxylin and eosin(HE) staining. The ratio of Th17 cells to mononuclear cells in the spleen was detected by flow cytometry. The level of IL-17 in bronchoalveolar lavage fluid(BALF) was measured by enzyme-linked immunosorbent assay(ELISA). The cell numbers in BALF were counted as total cells,eosinophils and neutrophils. Results:Elevated inflammation were observed in the lung and airway tissues of asthmatic mice when compared with controls. Not only the frequency of Th17 cells in spleen but also the level of IL-17 in BALF of asthmatic mice were significantly higher than those of normal controls(all P < 0.01). The numbers of total cells and eosinophils in BALF of asthmatic mice were significantly higher than those of normal controls(all P < 0.01). Conclusion:The study showed that the increasing number of Th17 cells in spleen and level of cytokine IL-17 in BALF are characteristic features in asthmatic mouse model. IL-17 may be associated with the recruitment of eosinophils into airways in asthma.These results demonstrate that Th17 cells may play an important role in the pathogenesis of asthma.