Antiphospholipid syndrome (APS) was first identified in patients with systemic lupus erythematosus (SLE) and frequent occurrence of thromboembolic complications and miscarriages accompanied by detection of anticardiolipin antibodies (aCL). When APS was also later found without an underlying SLE, the so-called primary APS was distinguished from its secondary form with SLE. Even more specific than aCL are the lupus anticoagulant (LA) and antibodies against beta‑2 glycoprotein I (aB2GP I). In recent years, it has become evident that the risk of (further) thromboembolic and obstetric complications is markedly increased if all three serological criteria of APS (aCL, aB2GP I and LA), the so-called triple positivity, are present (high-risk profile). Immunosuppression is not effective in preventing further thromboembolic complications of APS. Low-dose aspirin (LDA), heparin and vitamin K antagonists are used in primary and secondary prophylaxis. The direct oral anticoagulants have an increased risk of complications compared to these treatments and should not be used in cases of high-risk APS.