Better information on the financing of the health sector is an essential basis for wise policy change in the area of health sector reform. Analysis of health care financing should begin with sound estimates of national health expenditure--total spending, the contributions to spending from different sources and the claims on spending by different uses of the funds. The member countries of the OECD have successfully established such comparative health expenditure accounts in terms of standardized definitions of the uses of funds and breakdowns by public and private sector sources. This has resulted in important research on health system differences which could explain variations in the level and composition of financing. The United States has developed a more detailed approach called National Health Accounts, which expands the OECD method into a more disaggregated 'sources and uses' matrix. In the developing countries, analysis of health expenditures has been much less systematic, despite several decades of calls by international researchers for more attention. This paper reviews previous work done in developing countries and proposes renewed attention to national health expenditures, adapting the recent experience of the United States. Because most developing countries have more pluralistic health financing structures than are found in most industrialized countries, an enhanced and adapted version of the 'sources and uses' matrix method is proposed. This method should be modified to address the relevant categories of expenditures prevalent in the developing countries. Examples of recent applications of such 'national health accounts' from the Philippines, Egypt, India, Mexico, Colombia and Zambia are presented. Experience to date suggests that development of sound estimates using this method in low and middle income countries is feasible and affordable. National health accounts estimates can significantly influence policy. They provide decision makers with a holistic picture of the health sector, showing the actual emphasis of spending and the roles of different payers. They also provide a consistent framework for modelling reforms and for monitoring the effects of changes in financing and provision. An easy to use software tool has been developed for training and data management. Regional networks of collaborating national groups are proposed as a first step in expanding use of the method and to gain both national and cross-national comparative benefits.