Since 2000, more and more initiatives have been taken at the international and national levels in order to strengthen national health systems as the core components of the global health system. Having this scope in mind, it is essential to have a clear, and unrestricted, vision of national health systems that might generate further progresses in global health. The elaboration and the selection of performance indicators are indeed both highly dependent on the conceptual framework adopted for the evaluation of the health systems performances.  Like most social systems, health systems are complex adaptive systems where change does not necessarily follow rigid epidemiological models. In complex systems path dependency, emergent properties and other non-linear patterns are under-explored and unmeasured,  which can lead to the development of inappropriate guidelines for developing responsive health systems.