: The objective of the study is to perform a cost comparison of 1 year of oral anticoagulation management with warfarin vs. hypothetical rivaroxaban (RRX) in thrombotic primary antiphospholipid syndrome. Longitudinal study on 20 primary antiphospholipid syndrome patients followed-up for 1 year after anticoagulation stabilisation with warfarin: a dedicated software calculated number of clinic visits, time in therapeutic range and warfarin consumption for each patient; for RRX, we considered a visit every 3 months (baseline done in hospital before attending anticoagulant clinic); knowing the cost of both anticoagulants, the laboratory cost and the human cost we calculated and compared the yearly expenditure. Average time in therapeutic international normalized ratio range was 69 ± 11%: warfarin management required a total of 375 of visits compared with the 60 for RRX; the yearly cost of RRX was superior to that of warfarin (12 012 vs. 446.4 euros, P < 0.0001), and in spite of lower laboratory (738 vs. 1853 euros, P < 0.0001) and human costs (774.6 vs. 4841 euros), RRX thromboprophylaxis still yielded a hefty bill (13 525 vs. 7140 euros, P < 0.0001). Switching from warfarin to RRX will be 48% more expensive to our Healthcare Authority; unless ongoing clinical trials demonstrate improved long-term outcomes for RRX over warfarin, we feel that a 69% time in therapeutic range does not warrant a change to RRX at a 48% increased cost.