Objective:To observe the effects of imiquimod on airway hyperresponsiveness, airway remodeling and the expression of vascular endothelial growth factor(VEGF) in an asthmatic mouse model. Methods:Mice were randomly divided into a control group(A group), an asthmatic group(B group) and an imiquimod group(C group), each in ten. Mice were sensitized on days 0 and 14 by OVA and challenged from days 24 to 51 by OVA repeatedly to establish a chronic asthmatic model. C group were interfered with aerosol Imiquimod 30 min before challenge. A group was treated with saline instead of OVA. The airway resistance(Re) was measured with pulmonary function meter. Bronchial alveolar lavage fluid was performed and cell differential was examined by Wright-Giemsa staining; the vascular counts were measured by image analysis system. The protein expression of VEGF was determined by immunohistochemistry. The mRNA expression of VEGF was detected by RT-PCR. Results:Re of B group was higher than A group(P < 0.05), Re of C group was reduced compared with B group(P < 0.05). Total cell counts, EOS and lymphocyte in B group were higher than those in A group(P < 0.05),while decreased in C group(P < 0.05). in B group, the expressions of VEGF and mRNA increased when compared with A group(P < 0.05),and decreased in C group(P < 0.05). Conclusion:The experimental data suggest that imiquimod aerosol inhalation may inhibit airway hyperresponsiveness and airway remodeling, decrease the protein and mRNA expressions of VEGF in a mouse model of chronic asthma.