AIM: To investigate the effect of the dipeptide Arg-Gln on retinal neovascularization of retinopathy of prematurity (ROP) in the oxygen-induced retinopathy (OIR) animal model. METHODS: Forty-eight 7-day-old C57BL/6J mice were exposed to 750mL/L oxygen for 5 days and then to normal situation to produce the murine model of oxygen-induced retinopathy (OIR). All mice received twice daily intra- peritoneal injections of PBS or the dipeptide Arg-Gln (1.0, 3.0, 5.0g/kg per day), starting on postnatal day 12 and continuing till postnatal day 17. Experimental groups (36 mice, 12 in each group) received Arg-Gln, while the control group (12 mice) received PBS. All mice were executed at postnatal day 17. The changes of retinal vessels of mice were observed by ADPase histochemical technique and HE staining was used to count preretinal neovascular nuclei. RNA was isolated from retinas of 28 mice (7 in each group) selected at random and VEGF mRNA level of each group was measured by real-time RT-PCR. RESULTS: Neovascularization reduced in retinas of the dipeptide Arg-Gln treated group in a dose-dependent manner. Compared with control group, experimental group had diminished non-perfusion area and neovascular tufts in retinal flatmount. The number of the endotheliocyte nuclei of new vessels extending from retina to vitreous was significantly less in the eyes of the experimental group than in control group. Arg-Gln at 5g/kg per day reduced preretinal neovascularization by about 75% (P <0.01). There was a significant reduction in VEGF mRNA at the 17^th day in Arg-Gln treated group compared with control group(P ＜0.01). CONCLUSION: Arg-Gln dramatically inhibits retinal angiogenesis in OIR and this effect is associated with a reduction in retinal VEGF mRNA level. It appears to be a safe way to prevent and treat some neovascular retinal diseases including retinopathy of prematurity.