Cost is an implicit part of every medical decision, and therefore cost-effectiveness based decision-making is part of the rationing debate. Cost-effectiveness based decision-making in medicine has different, but parallel aims to evidence-based medicine (EBM), but also brings with it a new range of concerns and problems. Cost-effectiveness based medical decision-making (CEM) concerns itself with relative values for populations of patients, while EBM is concerned with absolute benefit to the individual. From the outset CEM is, by nature, concerned with utilitarian values in seeking maximal benefit for a group of individuals. CEM is a direct development of cost-effectiveness analysis. In CEM therefore the important values considered are the costs of the intervention, the magnitude of the treatment effects and the probabilities that the desired effects will be achieved. CEM does have the advantage that a wider range of values can be inserted into decisions.