The member States of the OEI are: Andorra, Argentina, Bolivia, Brazil, Chile, Colombia, Costa Rica, Cuba, Ecuador, El Salvador, Spain, Guatemala, Equatorial Guinea, Honduras, Mexico, Nicaragua, Panama, Paraguay, Peru, Portugal, Dominican Republic, Uruguay and Venezuela.
The OEI started cooperation activities with the European Institute of Cultural Routes (EICR) in 2018 and was granted “Participatory status” with the Enlarged Partial Agreement on Cultural Routes of the Council of Europe (EPA) in 2021.