The System of National Accounts (often abbreviated as SNA; formerly the United Nations System of National Accounts or UNSNA) is an international standard system of national accounts, the first international standard being published in 1953. Handbooks have been released for the 1968 revision, the 1993 revision, and the 2008 revision. The System of National Accounts, in its various released versions, frequently with significant local adaptations, has been adopted by many nations. It continues to evolve and is maintained by the United Nations, the International Monetary Fund, the World Bank, the Organisation for Economic Co-operation and Development, and Eurostat.

The aim of SNA is to provide an integrated, complete system of accounts enabling international comparisons of all significant economic activity. The suggestion is that individual countries use SNA as a guide in constructing their own national accounting systems, to promote international comparability. However, adherence to an international standard is entirely voluntary, and cannot be rigidly enforced. The systems used by some countries (for example, France, the United States, and China) differ significantly from the SNA. In itself, this is not a major problem, provided that each system provides sufficient data which can be reworked to compile national accounts according to the SNA standard.