Antiphospholipid syndrome is a condition with an increased propensity for both arterial and venous thrombosis. Compared with the normal population there is also a higher rate of recurrence. Most evidence exists for the use of warfarin in the secondary prevention of thromboembolism, aiming for an international normalized ratio between 2.0 and 3.0. Care must be taken with all anticoagulants because of the increased risk of bleeding. Several other strategies are available if warfarin fails, including the addition of aspirin, increasing the warfarin target range, and use of heparin.