Sheets of Portugal, 1991
| Issuer | Date | Desc | State | ||
| - |  |
Portugal | 2/7/1991 | empty sheet (#7991) | incomplete |
| - |  |
Portugal | 3/6/1991 | empty sheet (#7988) | incomplete |
| - |  |
Portugal | 3/6/1991 | empty sheet (#7989) | incomplete |
| - |  |
Portugal | 3/6/1991 | empty sheet (#7992) | incomplete |
| - |  |
Portugal | 4/11/1991 | empty sheet (#7993) | incomplete |
| - |  |
Portugal | 5/27/1991 | empty sheet (#7994) | incomplete |
| - |  |
Portugal | 5/27/1991 | Discovery Ships, sheet of 4 types | all added |
| - |  |
Portugal | 7/8/1991 | empty sheet (#7990) | incomplete |
| - |  |
Portugal | 10/9/1991 | empty sheet (#7995) | incomplete |
| - |  |
Portugal | 11/15/1991 | empty sheet (#7996) | incomplete |