Purpose: The purpose of this study was to compare the injection burden, central macular thickness (CMT), and change in best-corrected visual acuity (BCVA) after injecting 1.25 mg or 2.5 mg of bevacizumab as needed in patients with primary macular edema secondary to branch retinal vein occlusion. Methods: An interventional, retrospective, comparative multicenter study was conducted of 63 eyes with macular edema secondary to branch retinal vein occlusion that were treated primarily with intravitreal bevacizumab (38 eyes, 1.25 mg; 25 eyes, 2.5 mg). The main outcome measures were the CMT and the change of BCVA at 24 months.Results: All patients completed at least 24 months of follow-up. The mean number of injections per eye was 3.6 in the 1.25-mg group and 4.3 in the 2.5-mg group (P = 0.4770). At 24 months, in the 1.25-mg group, the logarithm of the minimum angle of resolution BCVA improved from baseline 0.38 +/- 0.63 (P < 0.0001) units to 0.64 +/- 0.6 units for the 2.5-mg group (P < 0.0001). In the 1.25-mg group, 26 (68%) eyes gained > or =3 of Early Treatment of Diabetic Retinopathy Study visual acuity and 2 (5%) eyes lost > or =3 lines of Early Treatment of Diabetic Retinopathy Study visual acuity. In the 2.5-mg group, 18 (72%) eyes improved > or =3 of Early Treatment of Diabetic Retinopathy Study visual acuity, and none of the eyes lost > or =3 lines of Early Treatment of Diabetic Retinopathy Study visual acuity. The CMT in the 1.25-mg group improved from 453 +/- 140 microm to 244 +/- 125 microm (P < 0.0001) versus 444 +/- 175 microm to 234 +/- 80 microm in the 2.5-mg group (P < 0.0001). There were no cases of endophthalmitis. No systemic adverse events were reported.Conclusion: Intravitreal bevacizumab at doses up to 2.5 mg seems to be effective in improving BCVA and reducing CMT in macular edema secondary to branch retinal vein occlusion. No statistically significant differences were found between the two dose groups with regard to the number of injections, CMT, and change in BCVA.