Antiphospholipid syndrome (APS) is an auto-immune syndrome defined by thrombosis and/or pregnancy morbidity in the persistent presence of antiphospholipid antibodies. Antiphospholipid antibodies are a group of antibodies predominantly directed at phospholipid-bound plasma proteins. The more antibodies a patient has the higher the risk of thrombosis. The origin of the antibodies and the precise prothrombotic mechanism are incompletely understood. A diagnosis of APS can in certain clinical scenarios implicate a longer treatment with anticoagulants after a venous thromboembolism. High level evidence is absent. In addition, APS patients with a high risk antibody profile had a higher risk of arterial thrombosis in randomized trials when treated with direct oral anticoagulants compared to vitamin K antagonists. The number needed to screen in light of these possible consequences of an APS diagnosis for treatment, appears to high to justify routine screening. In this review we suggest indications for APS testing in the context of venous thromboembolism.