Antiphospholipid syndrome (APS) is a clinical condition characterized by recurrent thrombotic events and/or pregnancy morbidity associated with the persistence of antiphospholipid antibodies (aPLs). It is the one of the most common diseases in acquired thrombophilia. In approximately 50 % of APS patients, systemic lupus erythematosus coexist. APS is diagnosed by the 2006 Sydney revised Sapporo criteria. The pathogenic processes of APS have not been fully elucidated. Multiple mechanisms have been proposed, including interference with hemostatic reactions, activation of endothelial cells and complement activation. The treatment of APS is virtually the preventive therapy such as long-term anticoagulation and the role of corticosteroid or immunosuppressive agents is limited.