[Advances and challenges in setting priorities in health]

The advances and problems in the definition of explicit criteria to measure health needs are discussed. In part one the advantages and limitations of the retrospective and prospective approaches in the identification of health needs for a rational distribution of resources are described. In part two progress in the application of explicit criteria for the prioritization of diseases and interventions to control them are analyzed. Finally, the methodological, conceptual, and operative challenges confronted by this field are discussed.