24 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 Pedro Eugenio Aramburu | | |
| | BOLIVIA | (Sucre cj + La Paz eir) | | President Hernan Siles Zuazo | | |
| | BRAZIL | (Rio de Janeiro) | | President Juscelino Kubitschek | | |
| | CHILE | (Santiago of Chile a + Valparaiso l + Vina del Mar s) | | President Carlos Ibanez del Campo | | |
| | COLOMBIA | (Bogota) | | Gabriel Paris Gordillo | | |
| | COSTA RICA | (San Jose) | | President Jose Figueres Ferrer | | |
| | CUBA | (Havana) | | President Fulgencio Batista | | |
| | DOMINICAN | (Ciudad Trujillo) | | Generalissimo Rafael Leonidas Trujillo | | |
| | ECUADOR | (San Francisco of Quito) | | President Camilo Ponce Enriquez | | |
| | FRENCH UNION | (Paris) | | President Rene Coty | | |
| | GUATEMALA | (Guatemala City) | | Carlos Castillo Armas | | |
| | HONDURAS | (Tegucigalpa a + Comayaguela c) | | Military Council of Government | | |
| | HAITI | (Port Au Prince) | | Executive Government Council | | |
| | MEXICO | (Mexico City) | | President Adolfo Ruiz Cortines | | |
| | NICARAGUA | (Managua) | | President Luis Somoza Debayle | | |
| | NETHERLANDS | (Amsterdam a + The Hague jlr + Wassenaar r) | | Queen Juliana | | |
| | PANAMA | (Panama City) | | President Ernesto de la Guardia | | |
| | PERU | (Lima) | | President Manuel Prado Ugarteche | | |
| | PARAGUAY | (Assumption) | | President Alfredo Stroessner | | |
| | EL SALVADOR | (San Salvador) | | President Jose Maria Lemus | | |
| | UNITED KINGDOM | (London a + Westminster lr + Edinburgh s + Windsor r) | | Queen Elizabeth II | | |
| | AMERICA | (Washington-District of Columbia) | | President Dwight David Eisenhower | | |
| | URUGUAY | (Montevideo) | | President Arturo Lezama | | |
| | VENEZUELA | (Caracas) | | President Marcos Perez Jimenez | | |