Haemophilic arthropathy is one of the major complications of severe haemophilia. In order to maintain plasma clotting factor activity levels above 1% and avoid spontaneous joint bleeds and other serious bleeding events, prophylactic factor replacement therapy is used. Because of the high cost and limited availability of clotting factor concentrates, dosing is a crucial issue for prophylaxis therapy. Several studies reported a better correlation between clinical bleeding tendency of patients with haemophilia and thrombin generation assay results compared to FVIII/FIX levels. However there is no specific data showing that thrombin generation may be a better indicator of the clinical efficacy of prophylaxis compared to the conventional FVIII measurement.