1960: Founding Members: Iran, Iraq, Kuwait, Saudi Arabia and Venezuela.
Qatar (1961);
Indonesia (1962) – suspended its membership from January 2009
Socialist Peoples Libyan Arab Jamahiriya (1962)
United Arab Emirates (1967)
Algeria (1969)
Nigeria (1971)
Ecuador (1973) – suspended its membership from December 1992-October 2007
Angola (2007)
Gabon (1975–1994).