Total Membership: 178 (as of 19 September 2023)
Eighteen ratifications were required to bring the IAEA's Statute into force on 29 July 1957.
In the list below, the year denotes year of membership. The names of States are not necessarily their historical designations.
- 1957: Afghanistan; Albania; Argentina; Australia; Austria; Belarus; Brazil; Bulgaria; Canada; Cuba; Denmark; Dominican Republic; Egypt; El Salvador; Ethiopia; France; Germany; Greece; Guatemala; Haiti; Holy See; Hungary; Iceland; India; Indonesia; Israel; Italy; Japan; Republic of Korea; Monaco; Morocco; Myanmar; Kingdom of the Netherlands; New Zealand; Norway; Pakistan; Paraguay; Peru; Poland; Portugal; Romania; Russian Federation; South Africa; Spain; Sri Lanka; Sweden; Switzerland; Thailand; Tunisia; Türkiye; Ukraine; United Kingdom of Great Britain and Northern Ireland; United States of America; Bolivarian Republic of Venezuela; Viet Nam
- 1958: Belgium; Ecuador; Finland; Islamic Republic of Iran; Luxembourg; Mexico; Philippines; Sudan
- 1959: Iraq
- 1960: Chile; Colombia; Ghana; Senegal
- 1961: Democratic Republic of the Congo; Lebanon; Mali
- 1962: Liberia; Saudi Arabia
- 1963: Algeria; Plurinational State of Bolivia; Côte d'Ivoire; Libya; Syrian Arab Republic; Uruguay
- 1964: Cameroon; Gabon; Kuwait; Nigeria
- 1965: Costa Rica; Cyprus; Jamaica; Kenya; Madagascar
- 1966: Jordan; Panama
- 1967: Sierra Leone; Singapore; Uganda
- 1968: Liechtenstein
- 1969: Malaysia; Niger; Zambia
- 1970: Ireland
- 1972: Bangladesh
- 1973: Mongolia
- 1974: Mauritius
- 1976: Qatar; United Arab Emirates; United Republic of Tanzania
- 1977: Nicaragua
- 1983: Namibia
- 1984: China
- 1986: Zimbabwe
- 1992: Estonia; Slovenia
- 1993: Armenia; Croatia; Czech Republic; Lithuania; Slovakia
- 1994: Kazakhstan; Marshall Islands; North Macedonia; Uzbekistan; Yemen
- 1995: Bosnia and Herzegovina
- 1996: Georgia
- 1997: Latvia; Malta; Republic of Moldova
- 1998: Burkina Faso
- 1999: Angola; Benin
- 2001: Azerbaijan; Central African Republic; Serbia; Tajikistan
- 2002: Botswana; Eritrea
- 2003: Honduras; Kyrgyzstan; Seychelles
- 2004: Mauritania
- 2005: Chad
- 2006: Belize; Malawi; Montenegro; Mozambique
- 2007: Palau
- 2008: Nepal
- 2009: Bahrain; Burundi; Cambodia; Congo; Lesotho; Oman
- 2011: Lao People's Democratic Republic
- 2012: Dominica; Fiji; Papua New Guinea; Rwanda; Togo; Trinidad and Tobago
- 2013: Eswatini; San Marino
- 2014: Bahamas; Brunei Darussalam
- 2015: Antigua and Barbuda; Barbados; Djibouti; Guyana; Vanuatu
- 2016: Turkmenistan
- 2017: Saint Vincent and the Grenadines
- 2018: Grenada
- 2019: Saint Lucia
- 2020: Comoros
- 2021: Samoa
- 2022: Saint Kitts and Nevis; Tonga
- 2023: Cabo Verde; Guinea, The Gambia
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Total Membership: 178 (As of 19 September 2023)
The Democratic People's Republic of Korea (DPRK), which joined the IAEA in 1974, withdrew its membership of the IAEA in 1994.
For the following States, membership has been approved by the IAEA General Conference and will take effect once the States deposit the necessary legal instruments with the depositary Government:
-- Cook Islands and Somalia.