RNA interference using small interfering RNAs which are specific for the vascular endothelial growth factor (VEGF) gene and the VEGF receptor genes Flt-1 and Flk-1/KDR inhibit expression of these genes. Diseases which involved angiogenesis stimulated by overexpression of VEGF, such as diabetic retinopathy, age related macular degeneration and many types of cancer, can be treated by administering the small interfering RNAs.