The 2003 edition of National Accounts of OECD Countries: Main Aggregates, Volume I covers expenditure based GDP, output based GDP, income based GDP, disposable income, saving and net lending, population and employment. It also includes comparative tables based on exchange rates and comparative tables based on purchasing power parities. Data are shown for 30 OECD countries and the euro area back to 1990 in most cases, expressed in national currency (in euros for euro area countries), but also in US dollars for gross domestic product and household final consumption expenditure back to 1979. These data are based on the System of National Accounts 1993 (1993 SNA) for a majority of countries, but not all. In this issue, the national accounts for two OECD countries (Switzerland and Turkey) are still presented on the basis of the 1968 SNA.