AIM: To evaluate the association between the size of peripheral retinal non-perfusion and the number of intravitreal ranibizumab injections in patients with treatment-naive branch retinal vein occlusion (BRVO) and macular edema. METHODS: A total of 53 patients with treatment-naive BRVO and macular edema were included. Each patient underwent a full ophthalmologic examination including optical coherence tomography (OCT) imaging and ultra wide-field fluorescein angiography (UWFA). Monthly intravitreal ranibizumab injections were applied according to the recommendations of the German Ophthalmological Society. Two independent, masked graders quantified the areas of peripheral retinal non-perfusion. RESULTS: Intravitreal injections improved best corrected visual acuity (BCVA) significantly from 22.23 +/- 16.33 Early Treatment of Diabetic Retinopathy Study (ETDRS) letters to 36.23 +/- 15.19 letters (P<0.001), and mean central subfield thickness significantly reduced from 387 +/- 115 mu m to 321 +/- 115 mu M (P=0.01). Mean number of intravitreal ranibizumab injections was 3.61 +/- 1.56. The size of retinal non-perfusion correlated significantly with the number of intravitreal ranibizumab injections (R=0.724, P<0.001). CONCLUSION: Peripheral retinal non-perfusion in patients with BRVO associates significantly with intravitreal ranibizumab injections in patients with BRVO and macular edema.