Haemophilia is a rare X-linked disease of coagulation, implying a partial or a complete deficiency of circulating factor VIII, in case of haemophilia A, or factor IX, in case of haemophilia B. If untreated, the bleeding tendency in patients with haemophilia may induce spontaneous bleeding episodes leading to serious complications, including premature death. Substitutive treatments consisting of intravenous infusions of clotting factor VIII or IX concentrates, which can be administered in a preventive or curative way, are presently available. To be effective, there is a need to administrate the correct dosing of clotting factors. The optimal substitutive treatment dosing of factor VIII concentrates in haemophilia A is addressed in relation to morphometric variables in the first section of this thesis. However, current treatments for haemophilia have some limitations and the development of new treatments through clinical studies would be beneficial. Factors influencing the motivation of patients to participate in clinical studies to develop new treatments are addressed in the second section of the thesis. Finally, this work was integrated in a general public health perspective by investigating the health and the economic burden of haemophilia in Belgium in the final section. The consumption of coagulation factors needed to treat haemophilia and its associated cost is steadily increasing in Belgium and other developed countries. For the first time the total economic burden of haemophilia in Belgium was estimated. In addition, the disease burden related to haemophilia in Belgium was quantified through Disability-Adjusted Life Year (DALY) calculations.