Twenty-one (21) of the Islamic Development Bank Member Countries are designated as least developed by the United Nations.
- Afghanistan
- Bangladesh
- Benin
- Burkina Faso
- Chad
- Comoros (the)
- Djibouti
- Gambia (the)
- Guinea
- Guinea-Bissau
- Mali
- Mauritania
- Mozambique
- Niger
- Senegal
- Sierra Leone
- Somalia
- Sudan (the)
- Togo
- Uganda
- Yemen