This paper examines principles of health care resource allocation based on axioms for individual preferences and distributive justice. We establish axioms for representing individual preferences by quality-adjusted life years (QALYs), as well as axioms for existence of a social welfare function depending only on QALYs. A symmetric Cobb-Douglas social welfare function is characterized by an axiom stating that social welfare is anonymous with respect to the distribution of individual life years. Replacing this axiom with an axiom of non-age dependence, we obtain a characterization of a utilitarian social welfare function with certain weights. Further, we give axioms for a social welfare function being a weighted sum of power transformations of individual QALYs