23 Members (excluding the associate or suspended members but including the countries represented on their behalf) [The rulers are not necessarily the representatives in the organisation. ] :
| | ARGENTINE | (Buenos Aires a + Olivos r) | | President Arturo Umberto Illia | | |
| | BOLIVIA | (Sucre cj + La Paz eir) | | President Victor Paz Estenssoro | | |
| | BRAZIL | (Brasilia) | | President Joao Goulart | | |
| | CHILE | (Santiago of Chile a + Valparaiso l + Vina del Mar s) | | President Jorge Alessandri | | |
| | COLOMBIA | (Bogota) | | President Guillermo Leon Valencia | | |
| | COSTA RICA | (San Jose) | | President Francisco Jose Orlich Bolmarich | | |
| | DOMINICAN | (Santo Domingo de Guzman) | | Donald Joseph Reid Cabral | | |
| | ECUADOR | (San Francisco of Quito) | | Ramon Castro Jijon | | |
| | FRANCE | (Paris) | | President Charles de Gaulle | | |
| | GUATEMALA | (Guatemala City) | | Alfredo Peralta Azurdia | | |
| | HONDURAS | (Tegucigalpa a + Comayaguela c) | | Oswaldo Lopez Arellano | | |
| | HAITI | (Port Au Prince) | | President Francois Duvalier Papa Doc | | |
| | MEXICO | (Mexico City) | | President Adolfo Lopez Mateos | | |
| | NICARAGUA | (Managua) | | President Rene Schick Gutierrez | | |
| | NETHERLANDS | (Amsterdam a + The Hague jlr + Wassenaar r) | | Queen Juliana | | |
| | PANAMA | (Panama City) | | President Roberto Francisco Chiari | | |
| | PERU | (Lima) | | President Fernando Belaunde Terry | | |
| | PARAGUAY | (Assumption) | | President Alfredo Stroessner | | |
| | EL SALVADOR | (San Salvador) | | President Julio Adalberto Rivera | | |
| | UNITED KINGDOM | (London a + Westminster lr + Edinburgh s + Windsor r) | | Queen Elizabeth II | | |
| | AMERICA | (Washington-District of Columbia) | | President Lyndon Baines Johnson | | |
| | URUGUAY | (Montevideo) | | President Luis Giannattasio | | |
| | VENEZUELA | (Caracas) | | President Raul Leoni | | |