Objective To investigate the effects of 1, 25-( OH) 2D3 on the expression of matrix metalloprotease-9 ( MMP-9) and nuclear factor κB ( NF-κB) activity in a murine model of chronic asthma. Methods BALB/ c mice were sensitized and challenged with ovalbumin to establish chronic asthmatic model. The animals were randomly divided into a control group, an asthma group and a VD group. Lung sections from the mice were stained by HE and Masson’s trichrome, respectively. Morphometric analysis of the stained sections was performed using computerized image analysis system. Nuclear translocation of NF-κB p65 was examined using Western blot. The level of IκBαwas detected with real-time quantitative PCR ( RTPCR) and Western blot. In addition, the expression of MMP-9 in both activity and mRNA level was detected by gelatin zymograph and RT-PCR, respectively. Results Prominent airway remodeling developed in the asthma group, including the inflammatory cell infiltration, subepithelial collagen deposition and increased airway smooth muscle mass. In contrast, 1, 25-( OH) 2D3 attenuated these established structural changes of the airways. Stimulation with OVA induced a 7. 87-fold increase in the MMP-9 activity compared with that in the control group, and 1, 25-( OH) 2D3 treatment only induced a 3. 46-fold increase in the MMP-9 activity compared with that in the control group ( P lt;0. 05) . The mRNA level of MMP-9 in the VD group ( 3.16 ± 0.09) was decreased compared with the asthma group ( 5.74 ±0.13) ( P lt;0.05) , but itwas still higher than that in the control group ( 0.57 ±0.08) ( P lt;0.05) . 1, 25-( OH) 2D3 reduced the nuclear translocation of NF-κB p65 while up-regulated the IκBα level in lung tissue of chronic asthma. Conclusions 1, 25- ( OH) 2D3 can inhibit the NF-κB activity and down-regulate the expression of MMP-9 in lung tissue of chronic asthma, thus alleviating the established chronic asthma-induced airway remodeling.