The antiphospholipid syndrome (APS) was reported in the early 1980s as the association of thrombosis, recurrent pregnancy loss in the presence of anticardiolipin antibodies (aCL) and/or lupus anticoagulant (LA). Since then, many other clinical manifestations have been associated with aPL. Almost any organ and tissue may be involved in the disease, including the brain, the heart, the kidneys, the placenta and many more. aPL are a heterogeneous group of autoantibodies that are detected by immunoassays and functional coagulation tests. The antigenic targets are negatively charged phospholipids and serum phospholipid-binding proteins. Despite the strong association between aPL and thrombosis, the pathogenic role of aPL in the development of thrombosis has not been fully elucidated. Proposed mechanisms include antibody-mediated interference with coagulation homeostasis, activation of platelets and endothelial cells and a T-cell immune response to serum phospholipid-binding proteins. The mainstay of therapy is anticoagulation, whereas immunosuppression seems to be ineffective. Recommendations for the management of thrombosis in the antiphospholipid antibody syndrome have been based largely on retrospective case series. Several prospective clinical trials are currently underway and their results will probably lead to a more precise therapeutic approach of this problem.