The following is a list of the major existing intergovernmental organizations (IGOs). For a more complete listing, see the Yearbook of International Organizations, which includes c25,000 international non-governmental organizations (INGOs), excluding for-profit enterprises, about 5,000 IGOs, and lists dormant and dead organizations as well as those in operation (figures as of the 49th edition, 2012/13).

Sl No. Organization Name Purpose Members Secretary General/Head HQ Founded in
1 United Nations (UN) To facilitate cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace 193 Member States Ban-Ki-Moon (South Korea) New York City, USA 1945
2 United Nations Security Council (UNSC) To maintain international peace and security 15 Member states (5 Permanent) NA (Changes every month) New York City, USA 1946
3 EU (European Union) To improve economic, technological, social co-operation among the European Countries 27 European Countries HQ- Brussels,Belgium 1993
4 Commonwealth of Nations To improve co-operation among the nations which were formerly part of the British Empire. 54 Countries Kamalesh Sharma (India) Marlborough House, London 1952
5 OSCE (Organization for Security and Co-operation in Europe) To handle issues such as arms control, human rights, freedom of the press and fair elections  56 Countries, 12 Partners Lamberto Zannier (Italy) Vienna, Austria 1973 (as CSCE) Renamed as OSCE in 1995
6 SAARC (South Asian association for Regional cooperation) To improve economic, technological, social, and cultural development among the South Asian nations 8 South Asian Countries Fathimath Dhiyana Saeed (Maldives) Kathmandu, Nepal 1985
7 World Bank To promote foreign investment, international trade and facilitate capital investment. 187 Countries Robert B. Zoellick (USA) Washington DC 1944
8 International Monetary Fund (IMF) To promote international economic cooperation and focus on exchange rate and the balance of payments 187 Countries Christine Lagarde (France) Washington DC 1944
9 WTO (world trade organization) To supervise and liberalize international trade. 153 Countries Pascal Lamy (France) Geneva , Switzerland 1995
10 NATO (North Atlantic Treaty Organization) Intergovernmental military alliance based on the North Atlantic Treaty 28 Countries Anders Fogh Rasmussen (Denmark) Brussels,Belgium 1949
11 OPEC (Organization of Petroleum Exporting Countries) To decide the production and supply of crude oil by the member countries 12 Countries Abdalla Salem el-Badri (Libya) Vienna, Austria 1960
12 OECD (organization for Economic cooperation and development) To stimulate economic progress and world trade. 34 Countries Jose Angel Gurria (Mexico) Paris,France 1948
13 APEC (asian pacific economic cooperation) To promote free trade and economic cooperation throughout the Asia-Pacific region 21 Countries HQ- singapore 1989
14 SCO (shanghai cooperation organization) To promote intergovernmental mutual security 6 Countries Muratbek Imanaliev(Kyragyzstan) Beijing,China 1996