In order to investigate the expression of leukemia inhibitory factor (LIF) in airway epithelial tissues of normal and asthmatic rats, the influence of dexamethasone and the role of LIF in pathogenesis of asthma, 30 Sprague-Dawley (SD) rats were randomly divided into 3 groups (10 for each group): normal group, asthma model group, and dexamethasone-interfered group. In asthmamodel group and dexamethasone-interfered group, asthma rat models were established by intraperitoneal (i.p.) injection of 10% ovalbumin (OVA) and challenge with 1% OVA via inhalation. Rats in dexamethasone-interfered group were pretreated with dexamethasone (2 mg/kg, i.p) 30 min before each challenge. The expression of LIF protein in lung was detected by immunohistochemistry. The results showed that LIF protein was mainly expressed in cytoplasm of bronchial epithelial cells. The expression of LIF protein in the airway epithelial tissue of asthma model group was significantly higher than that in normal group and dexamethasone-interfered group (P＜0.01), but there was no significant difference between normal group and dexamethasone-interfered group (P＞0.05). It was concluded that the expression of LIF was increased significantly in the airway epithelial tissue of the asthma rats, and dexamethasone could down-regulate the expression of LIF. It was suggested that LIF might play an important role in the pathogenesis of asthma as an inflammation regulator.