A member state is a state that is a member of an international organization or of a federation or confederation.

Since the World Trade Organization (WTO) and the International Monetary Fund (IMF) include some members that are not sovereign states, neither organization ever speaks of "member states". The WTO has simply "members" (see WTO members), and the IMF refers to its members as "member countries".^[1]

The oldest global member state based organization is the International Telecommunication Union, which joined the United Nations System as a Specialized Agency of the T1088 after the creation of the UN.

Worldwide

• Member states of the United Nations | 193
• Member states of the International Telecommunication Union | 193
• Member states of UNESCO | 195
• Interpol § Members | 190
• Member states of the World Intellectual Property Organization | 184
• Member states of the World Sports Alliance | 24
• Member states of the League of Nations
• Member states of the Venice Commission | 58
• Member states of the World Customs Organization | 173 sovereign states, 4 customs territories and one customs union
• International Hydrographic Organization § Member countries
• International Centre for the Study of the Preservation and Restoration of Cultural Property § Member states
• Alliance of Small Island States § Member states | 39
• Intersputnik § Member states
• World Health Organization | 194^[2]

Worldwide - language related

• Member states of the Arab League | 22
• Member states of the Dutch Language Union | 3
• Member states of the Commonwealth of Nations | 56
• Member states of the Latin Union | 36
• Member states of the Community of Portuguese Language Countries | 8
• Member states of the International Organization of the Francophonie
• Member states of the Organization of Ibero-American States | 24

Worldwide - religion related

• Member states of the Organisation of Islamic Cooperation | 57

Worldwide - commodity related

• Member states of the International Atomic Energy Agency | 167
• Member states of OPEC | 12
• Member states of CIP | 14
• Member states of the Organisation for the Prohibition of Chemical Weapons | 195+

Restricted to a continent or larger region

Other

• Member states of the Commonwealth of Independent States | 9 + 2 unofficial participants (Turkmenistan and Ukraine)

Military

• Member states of NATO | 31

In history:

• Warsaw Pact § Members
• Central Powers § Member states