Retinal vein occlusion (RVO) may affect the central vein (CRVO) or a branch, and occurs in healthy patients or in patients having an arterial risk profile rather than a venous one. Its prevalence is above 1% in subjects older than 40 years. RVO is a cause of painless unilateral vision loss of variable degree. Significant residual visual loss is frequent: it is one of the five main causes of unilateral blindness. The diagnosis is usually easy at fundus examination, which shows multiple hemorrhages, retinal and papillary edema, and venous dilations in the territory of the occluded vein. Its physiopathology remains unknown, the precise cause of flow obstruction being still undetermined. The median age of RVO patients is around 60 years, slightly younger for CRVO where several familial cases have been described. RVO is clearly associated with arterial hypertension and glaucoma, but not with thrombophilia. It is neither associated with cancer risk, nor with classical venous thromboembolism. The risk of ischemic neurovascular event might be doubled in patients aged less than 70 years with RVO. The course of the disease lasts several months, the most frequent complication is macular edema but the most feared is the occurrence of iris or retinal neovascularization (15-20% of CRVO cases). There is no efficient general treatment. A pan-photocoagulation of the retina is performed if a clear risk or early signs of neovascularization are found at follow-up examination. A significant but temporary improvement of vision can be achieved with intravitreal injections of corticosteroids in approximately half the cases of macular edema.