ObjectiveTo observe the effects of 1,5(OH)₂D₃ on the airway remodeling and the expression of PAI-1 in asthma rats. MethodsEighteen wistar rats were randomly divided into three group:the control group, the asthma model group, and the 1,5(OH)₂D₃ group.The asthma model was established by sensitization and challenged with ovalbumin,and the rats in the 1,5(OH)₂D₃ group injected 1,5(OH)₂D₃ before the challenge. The following parameters were measured:the protein expression of PAI -1 by immunohistochemistry and the level of PAI -1 by ELISA. the bronchial wall thickness by computer-assisted image analysis system. Results(1)the bronchial wall thickness in the asthma group was higher than in the other groups(P＜0.01).(2) The expression of PAI -1 in the asthma group higher than that in other groups(P＜0.01).(3)The lever of PAI-1 in plasma of asthma group was higher than that in other groups(P＜0.01). (4)There was a positive correlation between the activity of PAI-1 in rat lungs and the bronchial wall thickness(r=0.822 P＜0.01),the same between the level of PAI-1 in plasma and the bronchial wall thickness(r=0.942 P＜0.01)Conclusion1,5(OH)₂D₃ could decrease the expression of PAI-1 in lung tissues of asthmatic rats and the level of PAI-1 in plasma and inhibit airway remodeling.