Health care systems face ever changing and often competing demands for resources. For a health care system to be sustainable it must be able to pay for investment in buildings and equipment, training and remuneration of personnel and for drugs and other consumables. How these financial resources are generated and managed – the process of collecting revenue and pooling funds – raises important issues for policy-makers and planners. This policy brief aims to summarise these issues from an international perspective and consider how funding systems can be designed in order to achieve policy objectives. It looks first at the different sources of revenue and then at the impact of different systems of funding on specific objectives related to social policy, politics and economics. Finally, it considers implementation issues and some of the wider dimensions that policy-makers need to consider.