:The present study investigated the effects of subconjunctival injections of an anti-rat vascular endothelial growth factor anti-VEGF antibody on oxygen-induced retinopathy OIR in a neonatal rat model. OIR was induced by daily cycles of 80 oxygen 20.5 h , room air 0.5 h , and a progressive return to 80 oxygen 3 h for 12 days until postnatal day P 12 . On P12, rats received subconjunctival injections in their right eye of 0.1 or 1.0 g anti-VEGF antibody or 1.0 g goat IgG as a control . No injections were made into the left eye. On P18, rats were killed and their retinas were removed and at-mounted before being stained with adenosine diphosphatase. Retinal neovascularization NV was scored and the extent of avascular areas, as a percentage of total retinal area AVA , was determined using image analysis. Although there was a tendency for lower mean NV scores in eyes injected with 0.1 and 1.0 g anti-VEGF compared with control 4.3 1.1, 2.3 1.0, and 6.7 1.3, respectively ; n 10-13 , the difference failed to reach statistical signi cance. Similarly, although there was a tendency for mean AVA to be lower in the injected eyes for both the 0.1 and 1.0 g anti-VEGF groups compared with control 15 3 , 13 3 , and 25 4 , respectively ; n 10-13 , the differences were not signi cant. Similar tendencies were observed in the contralateral eyes. Although further studies using larger numbers of rats are needed to obtain statistically signi cant results, the results of the present study suggest that the subconjunctival injection of anti-VEGF antibody may prove to be a useful route of administration in conjunction with intravitreal injections, which are the generally used method at present. However, careful attention should be paid to the possibility of systemic side effects.