The aim of this study was to identify the short-term effect, safety, and durability of intravitreally injected bevacizumab in patients with macular edema (ME) caused by retinal vein obstruction (RVO) and diabetic macular edema (DME). We retrospectively evaluated 39 eyes of 36 patients, 14 with ME caused by RVO and 25 with DME, who received intravitreal bevacizumab (1.25 mg) and were followed up for at least 3 months. Monthly assessments examined safety, best corrected visual acuity with an ETDRS chart (logMAR), and central retinal thickness (CRT) using optical coherence tomography. No significant ocular or systemic side-effects were observed. The follow-up period was 5.4 +/- 1.1 months (mean +/- standard deviation). During follow-up, the mean number of injections was 1.4 +/- 0.5. The baseline mean logMAR was 0.91 +/- 0.51, and the mean CRT was 552.6 +/- 186.7 microm. At 1, 2, and 3 months, the mean logMAR was 0.67 +/- 0.46 (paired t test, P < 0.001), 0.66 +/- 0.46 (P < 0.001), and 0.69 +/- 0.45 (P < 0.001), respectively, and the mean CRT was 323.1 +/- 151.9 mum (P < 0.001), 324.6 +/- 136.9 mum (P < 0.001), and 382.5 +/- 130.4 microm (P < 0.001), respectively. Fourteen (14) of 34 eyes with more than 3 months of follow-up required a second injection at a mean 3.4 +/- 1.0 months after the initial injection. For both ME caused RVO and DME patients, a bevacizumab administration improved logMAR and CRT at each time point through to 6 months, except for logMAR in DME at 1 week (P = 0.081), 5 months (P = 0.130) and 6 months (P = 0.759). An intravitreal bevacizumab injection for ME caused by RVO and DME was safe and effective for improving visual acuity and reducing CRT.