The role of antiphospholipid syndrome (APS) in the pathogenesis of retinal vein occlusion has been discussed for several years. Conflicting results of the published studies are caused by small numbers of investigated patients and lack of control groups. We performed a meta-analysis of all case-control studies published up to July 2007 that investigated the prevalence of APS according to current diagnostic criteria for this syndrome.The results of meta-analysis show a significantly higher prevalence of APS in patients with retinal vein occlusion compared with controls. Patients with APS are treated with anticoagulants to reduce the risk of recurrence of thrombosis. Therefore, screening for APS seems to be indicated in all patients with retinal vein occlusion, and, in the case of a positive result, initiation of anticoagulation. For patients with retinal vein occlusion with APS, no data are currently available regarding the recurrence of thrombosis. To give a clear recommendation, a prospective randomized study is required to investigate the benefit of anticoagulation.