The United Nations comprise sovereign states and the world's largest intergovernmental organization. All members have equal representation in the United Nations General Assembly.

The Charter of the United Nations defines the rules for admission of member states. Membership is open to all states which accept certain terms of the charter and are able to carry them out. New members must be recommended by the United Nations Security Council. In addition to the member states, the UN also invites non-member states to be observer states at the UN General Assembly. A member state that has persistently violated the principles of the United Nations Charter can be expelled from the United Nations.

Membership The criteria for admission of new members to the UN are established in Chapter II, Article 4 of the UN Charter:

Membership in the United Nations is open to all states which accept the obligations contained in the present Charter and, in the judgment of the Organization, are able and willing to carry out these obligations. The admission of any such state to membership in the United Nations will be effected by a decision of the General Assembly upon the recommendation of the Security Council.

A recommendation for admission from the Security Council requires affirmative votes from at least nine of the council's fifteen members, with none of the five permanent members using their veto power. The Security Council's recommendation must then be approved in the General Assembly by a two-thirds majority vote.

In principle, only sovereign states can become UN members, and currently, all UN members are sovereign states. Although five members were not sovereign when they joined the UN, they all subsequently became fully independent between 1946 and 1991. Because a state can only be admitted to membership in the UN by the approval of the Security Council and the General Assembly, a number of states that are considered sovereign according to the Montevideo Convention are not members of the UN. This is because the UN does not consider them to possess sovereignty, mainly due to the lack of international recognition or due to opposition from one of the permanent members.

In addition to the member states, the UN also invites non-member states to become observer states at the UN General Assembly, allowing them to participate and speak in General Assembly meetings, but not vote. Observers are generally intergovernmental organizations and international organizations and entities whose statehood or sovereignty is not precisely defined.

Original members

The UN officially came into existence on 24 October 1945, after ratification of the United Nations Charter by the five permanent members of the United Nations Security Council (the Republic of China, France, the Soviet Union, the United Kingdom, and the United States) and a majority of the other signatories. A total of 51 original members (or founding members) joined that year; 50 of them signed the Charter at the United Nations Conference on International Organization in San Francisco on 26 June 1945, while Poland, which was not represented at the conference, signed it on 15 October 1945.

The original members of the United Nations were: France (then the Provisional Government), Russia (then the Soviet Union), China (then Republic of China), the United Kingdom, the United States—these first five forming the Security Council—Argentina, Australia, Belarus (then the Byelorussian SSR), Belgium, Bolivia, Brazil (then the Vargas Era Brazil), Canada, Chile (then the 1925–73 Presidential Republic), Colombia, Costa Rica, Cuba (then the 1902–59 Republic), Czechoslovakia (then the Third Republic), Denmark, the Dominican Republic, Ecuador, Egypt (then the Kingdom of Egypt), El Salvador, Ethiopia (then the Ethiopian Empire), Greece (then the Kingdom of Greece), Guatemala, Haiti (then the 1859–1957 Republic), Honduras, India (then the British Raj), Iran (then the Imperial State of Iran), Iraq (then the Kingdom of Iraq), Lebanon, Liberia, Luxembourg, Mexico, the Netherlands, New Zealand (then the Dominion of New Zealand), Nicaragua, Norway, Panama, Paraguay, Peru, the Philippines (then the Commonwealth), Poland (then the Provisional Government of National Unity), Saudi Arabia, South Africa (then the Union of South Africa), Syria (then the Mandatory Republic), Turkey, Ukraine (then the Ukrainian SSR), Uruguay, Venezuela and Yugoslavia (then the Democratic Federal Yugoslavia).

Among the original members, 49 are either still UN members or had their memberships in the UN continued by a successor state (see table below); for example, the membership of the Soviet Union was continued by the Russian Federation after its dissolution (see the section Former members: Union of Soviet Socialist Republics). The other two original members, Czechoslovakia and Yugoslavia (i.e., the Socialist Federal Republic of Yugoslavia), had been dissolved and their memberships in the UN not continued from 1992 by any one successor state (see the sections Former members: Czechoslovakia and Former members: Yugoslavia).

At the time of UN's founding, the seat of China in the UN was held by the Republic of China, but as a result of United Nations General Assembly Resolution 2758 in 1971, it is now held by the People's Republic of China (see the section Former members: Republic of China (Taiwan)).

A number of the original members were not sovereign when they joined the UN, and only gained full independence later:

Belarus (then the Byelorussian Soviet Socialist Republic) and Ukraine (then the Ukrainian Soviet Socialist Republic) were both constituent republics of the Soviet Union, until gaining full independence in 1991. India (whose territory at that time, before the Partition of India, also included the present-day territories of Bangladesh and Pakistan) was under British colonial rule, until gaining full independence in 1947. New Zealand, while de facto sovereign at that time, "only gained full capacity to enter into relations with other states in 1947 when it passed the Statute of Westminster Adoption Act. This occurred 16 years after the British Parliament passed the Statute of Westminster Act in 1931 that recognised New Zealand's autonomy. If judged by the Montevideo Convention criteria, New Zealand did not achieve full de jure statehood until 1947." However, the UN considers New Zealand to have been independent in 1945, at the time the UN was formed. The Philippines (then the Philippine Commonwealth) was a commonwealth with the United States, until gaining full independence in 1946.

Current members

+ Member state Date of admission Notes The General Assembly voted for admission on 9 November 1946.Afghanistan and the United Nations The United Nations currently does not recognize any person as the head of state of Afghanistan, nor does it recognize any other Afghan official as legitimate, having determined through a process involving two committees that the last officeholders lost their authority when the government the UN recognized, the Islamic Republic of Afghanistan, ceased to exist on 15 August 2021, and was therefore no longer official. UN legal and political experts made this determination when Haneef Atmar, who had been the recognized foreign minister, attempted to communicate with the UN in 2022. The country's temporary representative Naseer Faiq has been retained by default on the decision of the UN, against the wishes of Atmar and other members of the UN delegation. Faiq has since forcefully denied being a representative of the Islamic Republic, accusing its officials of corruption and claiming to represent Afghanistan independently. His voting rights in the General Assembly were suspended under Article 19 of the UN Charter in 2024.A decision on whether to credential appointees of the new Taliban authorities has been repeatedly deferred. Argentina and the United Nations Former member: Union of Soviet Socialist Republics and Armenia and the United Nations Australia and the United Nations Former member: Union of Soviet Socialist Republics, and Azerbaijan and the United Nations Bangladesh and the United Nations Former member: Byelorussian Soviet Socialist Republic Belgium and the United Nations Name was changed from Dahomey on 2 December 1975. Former member: Yugoslavia Brazil and the United Nations Name was changed from Upper Volta on 6 August 1984. Previously referred to as Cape Verde. On 24 October 2013, Cabo Verde requested that its name no longer be translated into different languages. Name was changed to the Khmer Republic on 7 October 1970, and back to Cambodia on 30 April 1975. Name was changed again to Democratic Kampuchea on 6 April 1976, and back to Cambodia on 3 February 1990. Previously referred to as Cameroun (before merging with Southern Cameroons in 1961). By a letter of 4 January 1974, the Secretary-General was informed that Cameroon had changed its name to the United Republic of Cameroon. Name was changed back to Cameroon on 4 February 1984. Canada and the United Nations Country known as Central African Empire from 20 December 1976 to 20 September 1979. China and the United NationsFormer member: Republic of China Colombia and the United Nations Previously referred to as the People's Republic of the Congo. Name was changed to Congo on 15 November 1971. Costa Rica and the United Nations Until 31 December 1985 referred to as Ivory Coast. Former member: Yugoslavia Former member: Czechoslovakia Name was changed from Czech Republic on 17 May 2016. Its nameplate continued to display Czech Republic until sometime in 2022. Democratic People's Republic of Korea Korea and the United Nations Country used the name Zaire from 27 October 1971 to 16 May 1997. Denmark Egypt and the United NationsFormer member: United Arab Republic Name was changed from Swaziland on 19 April 2018. Ethiopia and the United Nations Fiji and the United Nations France and the United Nations Former member: Union of Soviet Socialist Republics Former member: German Democratic Republic East Germany and West Germany were admitted separately on the same date; they unified in 1990; see also Germany and the United Nations. India and the United Nations Indonesia and the United Nations Previously referred to as Iran. By a communication of 4 November 1982, Iran informed the Secretary-General that it should be referred to as the Islamic Republic of Iran. Israel and the United Nations Japan and the United Nations Former member: Union of Soviet Socialist Republics Spelling was changed from on 20 June 1997. Former member: Union of Soviet Socialist Republics Name was changed from Laos on 2 December 1975. Lebanon and the United Nations Formerly recognised as the Libyan Arab Republic from 1969 after originally being admitted as Libya. By notes verbales of 1 and 21 April 1977, the Libyan Arab Republic advised that it had changed its name to the Libyan Arab Jamahiriya. On 16 September 2011, the UN General Assembly awarded the UN seat to the National Transitional Council, thereby restoring the original name of Libya.

On 12 December 2022, the Credentials Committee deferred a decision on allowing the Government of National Stability to represent Libya at the U.N., allowing the Government of National Unity to retain the seat. Liechtenstein and the United Nations Luxembourg and the United Nations Malaysia and the United NationsName was changed from Federation of Malaya on 16 September 1963, following the admission to the new federation of Singapore, Sabah and Sarawak. Name was changed from Maldive Islands on 14 April 1969. Marshall Islands and the United Nations Mexico and the United Nations Federated States of Micronesia and the United Nations Former member: Yugoslavia, Serbia and Montenegro Name was changed from Burma on 17 June 1989.