The adequacy of the concept of willingness to pay within health economics evaluations is reviewed. A considerable number of researchers in the literature have pointed out multiple methodological issues involving willingness-to-pay estimates. On the other hand, the theoretical discussion about the aggregation of individual preferences within an aggregate demand remains open. However, over the last 20 years, willingness-to-pay estimates alongside health economics research significantly increased and in many cases they are one of the key factors for decision making on issues of health policies. The article describes some limitations of this approach as well as the potential distorting effect that it might have on health economics evaluations.