Retinopathy of prematurity (ROP) is one of the leading causes of blindness in preterm Infants. Anti-vascular endothelial growth factor (VEGF) is emerging as a promising treatment, but there is insufficient evidence on their safety. We investigate the effect of systemic anti-VEGF in rat pups with equivalent maturity to a 32 week neonate. A single dose of either anti-VEGF antibody (n = 7) or saline (control group; n = 6) was administered to newborn rats intra-peritoneally on the first day of life. 14 days' post treatment, the serum concentration of anti-VEGF was measured and the brain, lung, heart, kidney and liver were harvested and weighed. The heart was processed to measure the Fulton index (a surrogate for pulmonary hypertension). All other organs were processed for mRNA expression of VEGF and VEGF-receptors (R1&R2). No group differences in body and organ weights were noted. The anti-VEGF was still detected in serum 14 days post Injection and resulted in increase in lung (p < 0.002) and kidney (p < 0.01) VEGF mRNA expressions and the lung (p < 0.02) VEGF-R1 and kidney (P < 0.001) VEGF-R2 mRNA expressions. The treated pups exhibited increased total heart weight (p < 0.01) and Fulton Index (p < 0.05). No changes were seen in the liver and brain. Anti-VEGF antibody did not affect mortality, total body and organ weights, but was associated with pulmonary hypertension. Expression of lung and kidney VEGF and its receptors was increased, whilst the brain and liver did not show changes. Dosing experiments can now be targeted to assess safety threshold and at anti-VEGF dose used in human ROP treatment.