PURPOSE: To evaluate intravitreal injection of ranibizumab as a potential treatment for decreased visual acuity (VA) secondary to central retinal vein occlusion (CRVO). DESIGN: Prospective, interventional case series. METHODS: Patients with CRVO prospectively recruited from a practice were administered intravitreal ranibizumab 0.5 mg (Lucentis; Genentech Inc, South San Francisco, California, USA) at baseline and monthly for two additional doses. The patients were given additional ranibizumab if they had macular edema as determined by optical coherence tomography or any new intraretinal hemorrhage. Patients were evaluated for number of required injections, side effects, changes in VA, and macular thickness. RESULTS: There were 20 eyes of 20 patients who at baseline had a mean age of 72.1 years, a mean VA of 45.8 Early Treatment of Diabetic Retinopathy letters, and a mean central macular thickness of 574.6 microm. Of the 20 eyes, five previously had received intravitreal triamcinolone and 11 had received intravitreal bevacizumab (Avastin; Genentech Inc). At 12 months of follow-up, the mean VA improved to 64.3 letters and the central macular thickness decreased to 186 microm (both different than baseline values; P < .001) using a mean of 8.5 injections. The change in macular thickness was not correlated with the change in VA. In one patient with a history of transient ischemic attack, an ischemic stroke developed but no sequela resulted. In another patient, vitreomacular traction developed, but the patient had improved acuity as compared with baseline. There were no infections, retinal tears, or detachments. CONCLUSIONS: Intravitreal ranibizumab used over a period of one year improved mean VA, with low rates of adverse events, in patients with CRVO.