Objective · To study the effect of inhibitor of differentiation 1 (ID1) on ocular neovascularization. Methods · The oxygen-induced retinal neovascularization (OIR), laser-induced choroidal neovascularization (CNV) and over- of vascular endothelial growth factor (VEGF) (Rho-VEGF) transgenic mice were established. The localization and mRNA level of ID1 in retina of OIR mice and Rho-VEGF transgenic mice were determinedimmunofluorescence staining and quantitative real-time PCR. Mice deficient in ID1 (ID1./.) were used to induce retinal neovascularization in accordance with the above three models, and to compare the changes of ID1 on the number of retinal, subretinal and choroidal neovascularization areas. Into explore the role ID1 in neovascularization, the numbers and areas of retinal, subretinal and choroidal neovascularization in the mice models with or without ID1 deficiency were compared. Its effect on the related factors, i.e. hypoxia-inducible factor-1α (HIF-1α), VEGF and vascular endothelial growth factor receptor 1/2 (VEGFR1/2) were also observed. Results · Mice deficient in ID1 showed a significant reduction in the area of neovascularization in these three models(P<0.05). Mice lacking ID1 showed reduced levels of HIF-1α, VEGF and VEGFR 1. Conclusion · ID1 promotes the of HIF-1α, VEGF and VEGFR1 in the retina and choroidal neovascularization during hypoxia and oxidative injury. [Key words]inhibitor of differentiation-1 (ID1); ocular neovascularization; hypoxia-inducible factor-1α (HIF-1α); vascular endothelial growth factor