| Name | Issues/Designs | |||
| Ralph Bunche birth | 1903 | — | - 100th Anniversary of the Birth of ... | |
| UNHCR founding | 1951 | — | - 50th Anniversary of ... | |
| UNICEF founding | 1946 | — | - 50th Anniversary of ... syns. United Nations International Children's Emergency Fund founding | |
| UN founding | 1945 | — | (4) - UN 35th, 30th Anniversary of the ..., 55th Anniversary of the ..., ... syns. UNO founding | |
| United Nations Postal Administration founding | 1951 | — | - 50th Anniversary of the ... | |
| U.P.U. founding
(syn. of Universal Postal Union founding) |
1874 | — | - 100th Anniversary of UPU | |
| UPU founding
(syn. of Universal Postal Union founding) |
1874 | — | - 125th Anniversary of the ... |