Background: To evaluate the efficacy of intravitreal aflibercept injection in eyes with macular edema due to retinal vein occlusion (RVO). Patients and Methods: prospective, non-randomized clinical study included 60 eyes of 60 patients with macular edema due to RVO. Thirty patients had branch RVO (BRVO) and 30 had central RVO (CRVO). Each patient had received intravitreal injection of aflibercept once followed by re-evaluation of BCVA and CMT monthly during the follow up period up to 6 months after injection. Results: One month after IV aflibercept injection in patients with RVO ≤ 3 months, the main best-corrected visual acuity improved from 1.05±0.004 µm at baseline to 0.75±0.07 logMAR at 1 month, to 0.58±0.10 logMAR at 3^rd month and at the 6th month improved to 0.45±0.14 logMAR (p≤0.05). On the other hand, the mean BCVA improved from 1.40±0.03 µm at baseline to 1.13±0.07 logMAR at 1 month, to 0.98±0.06 logMAR at 3^rd month and to 0.92±0.08 logMAR at 6^th month (P≤ 0.05) in patients with RVO > 3 months. The mean central macular thickness reduced from 485.57±71.51 µm at baseline to 316.78±58.38µm (P≤0.05) after 1 month, to 259.45±50.84µm (P≤0.05) at the 3^rd month and to 225.85±34.44µm (P≤0.05) at 6^th month in patients with RVO ≤ 3 months. Meanwhile, in those with RVO > 3 months the main CMT reduced from baseline 625.91±167.56µm to 395.07±98.89µm (P≤0.05), to 319.53±53.28µm (P≤0.05) and at the 6th month reduced to 276.50±38.89 µm (p≤0.05). No intra-operative or post-operative complications as retinal detachment, vitreous hemorrhage, or elevated intraocular pressure. Subconjunctival hemorrhage or local hyperemia at the injection site may be observed in some cases. Long term duration without treatment is associated with less improvement in the visual acuity. Conclusion: Intravitreal injection of aflibercept is more clinically effective and generally well tolerated for treatment of macular edema due to RVO.