Most health economists agree that public preferences should play a major role in setting criteria for distributing scarce resources. The quality-adjusted life year (QALY) is used as a preference-based measure for the outcome of health-care activities in health economic evaluative studies. Traditionally, health economists proposed maximizing the additional health gain in terms of QALYs so as to maximize social welfare. Evidence has grown however, that neither potential health gain as a single relevant determinant of value, nor the rule of maximizing this health gain are sufficient. Concerns about fairness and equity are also important to the public in distributional decisions. This paper reviews the debate on the role and limitations of the QALY in health-care priority setting and the empirical evidence surrounding it. A framework is used to systematically explore the available data on factors considered to be important to the public in health-care resource allocation, and to investigate how these fit with the implicit value judgements inherent in the original QALY formulation. Potential sources of social value are classified into (1) factors that relate to the characteristics of patients and (2) factors related to the characteristics of the intervention's effect on patients' health. As well as these main categories, the article considers preferences for distributional rules. Recent approaches that aim to capture public preferences more comprehensively and to better reflect the value attributed to different health-care programmes in economic evaluation methods are outlined briefly.