This study presents an empirical investigation of differences in health care expenditure between the 26 federal entities of Switzerland in the 1990s. So far, demand and supply-related factors have dominated the debate, while political determinants have largely been neglected. Here, they will be assessed together with the usual indicators on the basis of a cross-sectional analysis of both public and private health care spending. It will be shown that no approach represents the whole truth, but each one a grain of it. Demand for health care is clearly a function of socio-economic factors. On the supply side, it is mainly the number of practitioners and the overall level of provision that drive costs. Finally, from the political factors, general state interventionism is decisive – though only so far as public spending is concerned.