Antiphospholipid antibody syndrome (APS) is characterised by the presence of frequently recurring venous and/or arterial thrombosis, abortions and repeated evidence of lupus anticoagulants and/or anticardiolipin (aCL)-antibodies. The presence of lupus anticoagulants and/or high levels of aCL-antibodies in particular increases the risk of thrombosis. At present there are several models for the systemic and cell-damaging pathogenesis of phospholipid-antibodies. Where there are repeated occurrences of thrombo-embolic complications long-term anticoagulant treatment is indicated. For patients who have APS in pregnancy, the use of low-molecular heparin and acetylsalicylic acid (ASS) is recommended. According to recent research, a large number of antibodies can be found in APS patients, which are directed against phospholipids and plasmaproteins, but partly also against individual genetic polymorphism, which suggests focussing in future on the genetic basis of APS as well as on influencing "auto-immune thrombosis" by modulating the immune system.