Healthcare costs are a concern for the sustainability of health systems in both rich and poor countries. Achieving a balance between the aspirations of payers and the manufacturers of new technologies is a challenge for democratic societies. Evidence about the efficacy and effectiveness of a new intervention is a fundamental aspect for its inclusion, but additional information about organization, implementation, and feasibility is required. Economic evaluations, especially cost-effectiveness analyses (CEA), help inform the choice of a particular health intervention, but they are not the only input for decision making (DM). Use of CEA is relatively recent but has quickly become widespread. CEA techniques have evolved into increasingly complex and sophisticated methods intended to reflect reality closely but, at the same time, their results have become more difficult to verify and validate. In developed countries, CEA results have generated intense debates, but in developing countries, these reflections are still weak due to lack of technical capacity. Competing perspectives on CEAs exist and can heavily influence the DM process. The use of CEAs and the interpretation of their results requires critical analysis, especially when public funds are to be invested. Here, we present a perspective on the use of CEAs for DM that arises from our experience of its use in developing countries and requires the consideration of other rationalities, in addition to the economic one, for DM.