In the framework of the DFG-Research-Unit 597 “Transformation of the State” is Project C3 investigating the change of the role of the state in health care systems in OECD-countries between 1970 and 2000. The primary research hypothesis is, that a tendency of convergence exists regarding the role of the state for the three main dimensions of health care systems, namely service provision, financing and regulation. This is carried out firstly based on a quantitative oriented analysis for 23 OECD-countries, utilising the data set “OECD Health Data 2002”, and secondly with qualitative oriented country-studies for England, Germany and the U.S. Findings for the qualitative country-studies give some hints of convergence regarding the “private-public-mix” between the health system types “social insurance” (Germany), “national health system” (England), and “market oriented health system” (USA). First quantitative results concerning the changing role of the state in relation to the health care systems in OECD-countries provide evidence for a convergence process between these states in the financing dimension. For the dependent variable “total health care costs in % of gross domestic product” a trend of convergence is observed for the members states of the European Union (n = 12), while in the remaining Non-EU countries (n = 11) a trend of divergence is identified. For the same parameter we found a convergence for OECD-countries of the type “national health system” (n = 14). For OECD-countries of the type “social insurance” (n = 8) this convergence process is observed only for the time period 1970 - 1980. Some results confirm the hypothesis of the “growth to limits” (Flora). But it appears to us that in future other significant factors like globalisation processes, the increasing potentials of the medical technology and demographic changes may play an important role for the overall health budget and specific needs of the population in the OECD-states.