Rising health care spending is putting pressure on government budgets. Governments will have to make their health care systems more efficient if they are to maintain quality of care without putting further stress on public finances. The OECD has assembled new comparative data on health policies and health care system efficiency for its member countries. These show that all countries surveyed can improve the effectiveness of their health care spending. If all countries were to become as efficient as the best performers, life expectancy at birth could be raised by more than two years on average across the OECD, without increasing health care spending. There is no single type of health care system that performs systematically better in delivering cost-effective health care, as both market-based and more centralised command-and-control systems have strengths and weaknesses. It seems to be less the type of system that matters, but rather how it is managed. Policy makers should aim for policy coherence by adopting best practices from other health care systems and tailoring them to their own circumstances. Nevertheless, the international comparison highlights a number of sources of potential efficiency gains, such as from improving to co-ordination of the bodies involved in health care management, strengthening gate-keeping, increasing out-of-pocket payments, enhancing information on quality and prices, reforming provider payment schemes or adjusting regulations concerning hospital workforce and equipment. By improving the efficiency of the health care system, public spending savings would be large, approaching 2% of GDP on average across the OECD.