Horn of Africa

• Djibouti (founding member, since 1986)
• Ethiopia (founding member, since 1986)
• Somalia (founding member, since 1986)
• Eritrea (admitted 1993, withdrew 2007, readmitted 2011)

Nile Valley

• Sudan (founding member, since 1986)
• South Sudan (admitted 2011)

African Great Lakes

• Kenya (founding member, since 1986)
• Uganda (founding member, since 1986)