PURPOSE. To investigate the effect of nontargeted siRNAs on vascular leakage and vascular endothelial growth factor (VEGF)-A expression in the development of choroidal neovascularization (CNV). METHODS. Nontargeted siRNAs were 21-nt (nucleotides) siRNA-Luc (Luciferase) or 16-nt siRNA-Luc. Targeted 21-nt siRNA-Vegfa or phosphate-buffered saline (PBS) was used for comparison. Laser photocoagulation was used to induce CNV in wild-type C57BL/6J mice; 7 days later, vascular leakage was determined by fluorescein angiography, and CNV volumes were measured by confocal microscopy. Expression of VEGF-A in the retinal pigment epithelium (RPE)/choroid was quantified by ELISA 3 days after photocoagulation. RESULTS. Pathologically significant leakage developed in most of the 16nt-siRNA-Luc- or PBS-injected mice but in significantly fewer 21nt-siRNA-Luc- and 21nt-siRNA-Vegfa-injected mice (P = 0.0004, P = 0.0001, respectively). CNV volume in 21-nt siRNA-Luc- and 21nt-siRNA-Vegfa-injected eyes was significantly lower than in PBS-injected eyes (P = 0.0124, P = 0.0040, respectively). CNV volume was not suppressed by 16-nt siRNA-Luc injection (P = 0.7700). The mean VEGF protein level decreased significantly in the 21nt-siRNA-Luc- and 21nt-siRNA-Vegfa-injected eyes compared with PBS-injected eyes 3 days after laser photocoagulation (P = 0.0011, P = 0.0063, respectively). The 16nt-siRNA-Luc-injected eyes did not show VEGF-A suppression 3 days after laser photocoagulation (P = 0.3177). Between 21-nt siRNA-Luc- and 21nt-siRNA-Vegfa-injected eyes, there were no significant differences in CNV volume, the VEGF-A level, or pathologic leakage detected by fluorescein. CONCLUSIONS. These data suggest that nontarget 21nt-siRNA can suppress laser-induced choroidal neovascularization anatomically and functionally through VEGF suppression.