An important consideration when establishing priorities in healthcare is the likely effect that alternative allocations will have on the health-related quality of life (HR-QOL) of the relevant population. This paper considers some of the important issues and controversies surrounding the valuation of HR-QOL. It considers the theoretical and empirical evidence regarding 3 crucial questions: (i) what is to be valued?; (ii) how is it to be valued?; and (iii) who is to value it? Many important yet unresolved issues emerge and directions for future research are suggested. It is argued that this research agenda should have the gathering and analysis of qualitative data at its forefront.