Primary prophylaxis with clotting factor is the clinical treatment of choice for people with severe haemophilia, as evidence suggests it can prevent the onset and progression of joint- and muscle-related problems caused by bleeding episodes. However, the major limitation of this approach is that it requires considerably more clotting factor compared with treating on-demand. Thus, there is a need to establish its cost-effectiveness. The aim of this paper is to review the published evidence on the cost-effectiveness of prophylaxis and to highlight areas for future research that would decrease the uncertainty around these findings.