Objective:To investigate the effects of H1-receptor (H1R) antagonists on the airway inflammation of asthmatic guinea pigs. Methods:The guinea pigs were divided into 3 groups: loratadine treated group (2 mg.kg-1.d-1),normal saline group (1 ml/d), and ketotifen treated group (0.1 mg.kg-1.d-1). The following tests were performed in 3 groups. (a)The ICAM-1, P-S,IL-8 and ECP values both in plasma (or serum )and BALF were measured by ELISA. (b)The expression of ICAM-1 and IL-8 on the bronchial epithelial cells and pulmonary vascular endothelial cells were measured by immunohistochemistry staining. (c)The expression of ICAM-1 on the leukocytes were measured by FCM. (d)The lung functions(Vt, Cdyn, Raw)were tested. (e)The airway tissues were examined by microscope and TEM. Results:(a)Apart from the values of IL-8 in BALF level of ketotifen group, the values of sICAM-1, sP-S,IL-8 and ECP were reduced by 2 kinds of H1R antagonists(loratadine and ketotifen)both in the plasma(or serum)and BALF of asthmatic animals. (b)The expressions of ICAM-1 and IL-8 on the brochial epithelial cells and pulmonary vascular endothelial cells in asthmatic animals were down-regulated by 2 kinds of H1R antagonists especially loratadine. (c)The expressions of ICAM-1 on the leukocytes were down-regulated by 2 kinds of H1R antagonists. (d)The lung functions (Vt, Cdyn, Raw) of the asthmatic animals were improved by 2 kinds of H1R antagonists.(e)The infiltration in the bronchial mucosa and the degranulation of eosinophils were reduced by 2 kinds of H1R antagonists.