[The concept of equity and the debate about fairness in health].

This work deals with understanding equity in health within the framework of an ethical-political discussion of justice; current debate on this issue is reviewed and the implications in defining public policy and organising health service systems are shown. The debates historicity and how it is carried out in contemporaneous societies is presented so that one or another positions predominance is a historical result depending on power relationships and correlating efforts within each society, within the framework of global interdependency. A process of democratic construction is thus suggested, based on the foregoing, for advancing towards a new configuration of equity in health for Latin-American countries.