Objective:To explore whether hypoxia-inducible factor-1α(HIF-1α)mediates hypoxic proliferation in airway smooth muscle cells(ASMC). Methods:Rat ASMC were incubated in vivo and grouped in three:ASMC that is cultured under normoxia was defined as control group(A group),ASMC that is cultured under hypoxia was defined as pure hypoxia group(group B),ASMC that is cultured under hypoxia and pretreated with 2-methoxyestradiol(2ME),which is inhibitor of HIF-1α,was defined as hypoxia and 2ME pretreatment group(group C). Proliferation of ASMC was evaluated by MTS. Real-time PCR and Western blot were used to analyze expression of HIF-1α mRNA and protein. Results:①The proliferation of rats ASMC is significantly higher in group B than that in group A(1.123 ± 0.006 vs 0.809 ± 0.003,P < 0.05),but it is significantly lower in group C than that in group B(1.012 ± 0.005 vs 1.123 ± 0.006,P < 0.05). ②Expression of HIF-1α mRNA and protein increased significantly in group B than that in group A(5.265 ± 0.040 vs 0.449 ± 0.017,P < 0.05 and 0.905 ± 0.013 vs 0.105 ± 0.008,P < 0.05),and decreased significantly in group C than that in group B(1.903 ± 0.044 vs 5.265 ± 0.040,P < 0.05 and 0.278 ± 0.012 vs 0.905 ± 0.013,P < 0.05),expression of HIF-1α mRNA(r = 0.850)and protein(r = 0.883) in ASMC correlated significantly with proliferation. Conclusion:HIF-1α mediated rat ASMC proliferation under hypoxia.