Ranibizumab (Lucentis®), a recombinant humanized IgG(1) κ isotype monoclonal antibody fragment, is approved in the US for the treatment of macular oedema following retinal vein occlusion (RVO). It binds to the receptor-binding site of active forms of vascular endothelial growth factor-A, inhibiting its biological activity. In two large, well designed, phase III trials in patients with macular oedema following branch RVO (BRVO) or central RVO (CRVO), monthly intravitreal injections of ranibizumab 0.5 mg were associated with significantly greater improvement from baseline in mean best-corrected visual acuity letter score (measured on the Early Treatment Diabetic Retinopathy Study chart) in the study eye at 6 months (primary endpoint) than sham injections. Moreover, ranibizumab was significantly more effective than sham injections with regard to improvements in central foveal thickness at 6 months, as well as several other visual acuity measures. Ranibizumab was generally well tolerated in patients with macular oedema following CRVO or BRVO. Overall, the most common adverse events with ranibizumab were consistent with the adverse event profile previously reported in patients with age-related macular degeneration.