This article examines the development of health system metrics by international organizations, exploring their relationship to the politics of world health. Current historiography treats measurement either as progressive illumination or adopts a critical stance, viewing indicators as instruments of global governance by powerful nations. We draw on diverse statistical publications to provide an empirical overview of change and continuity, beginning with the League of Nations Health Organization, which initiated health system statistics, and concluding with the World health report 2000, with its controversial comparative rankings. We then develop analysis and explanation of these trends. Population indicators appeared consistently owing to their protective function and compatibility with development thinking. Others, related to provision, financing, and coverage, appeared more sporadically, owing to changing trends and assumptions in international health. While partly affirming the critical literature, metrics were also used by peripheral or resistant actors to challenge or influence policy at the centre.