Clinical studies have shown significant improvement in outcomes with the use of prophylactic treatment, as well as apparent gains in health-related quality of life. Given the high cost and still limited availability of factor concentrates, physicians, insurers and governments require cost-effectiveness data to evaluate competing treatments (eg prophylactic vs. on-demand treatment) and to set priorities within the context of each country's financial resources. To date, the few published studies of the cost-effectiveness of haemophilia prophylaxis have generally focused on the reduction in frequency of bleedings as an intermediate outcome, and not on long-term health outcomes, such as the development of arthropathy and its social and economic costs. Since all prophylactic measures are investments for the future, long-term economic consequences need to be carefully studied and evaluated.