Prophylaxis is an expensive form of management in haemophilia but has demonstrated many advantages with respect to decreasing joint bleeds and potentially preventing joint damage. The valuation of prophylaxis and how the costs and benefits of this intervention compare with other interventions in the management of haemophiliacs can be evaluated through cost-utility analysis (CUA). CUA is an economic method of analysis where the benefits of a healthcare intervention are expressed as an overall utility or preference, usually in the form of quality-adjusted life years (QALYs). This is a composite measure, which takes into consideration both an individual's lifespan and quality of life (QoL). The most difficult aspect of performing a CUA is the measurement of health-related QoL (HRQoL). Much work is ongoing into evaluating HRQoL in haemophiliacs. This paper addresses some of the ways in which this can be achieved and some of the problems with evaluating HRQoL. Ultimately CUA may provide a tool to allow societies to decide if prophylaxis is worth the cost and how the costs and benefits of prophylaxis compare to other healthcare interventions for other disease entities.