| 1. Round | 07/08/1998 | Trabzonspor | - | Gaziantepspor | 0:1 | ||||
| 2. Round | 15/08/1998 | Gaziantepspor | - | Sakaryaspor | 2:0 |  |
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| 3. Round | 22/08/1998 | Beşiktaş | - | Gaziantepspor | 1:1 | ||||
| 4. Round | 29/08/1998 | Gaziantepspor | - | MKE Ankaragücü | 1:0 | ||||
| 5. Round | 12/09/1998 | Antalyaspor | - | Gaziantepspor | 3:1 | ||||
| 6. Round | 19/09/1998 | Gaziantepspor | - | Dardanelspor | 1:0 | ||||
| 7. Round | 26/09/1998 | Gaziantepspor | - | Altay Izmir | 1:1 | |
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| 8. Round | 17/10/1998 | Bursaspor | - | Gaziantepspor | 2:1 | ||||
| 9. Round | 24/10/1998 | Gaziantepspor | - | Kocaelispor | 1:2 | |
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| 10. Round | 30/10/1998 | İstanbulspor AŞ | - | Gaziantepspor | 0:0 | ||||
| 11. Round | 07/11/1998 | Gaziantepspor | - | Erzurumspor (1968-2015) | 3:0 | ||||
| 12. Round | 13/11/1998 | Fenerbahçe | - | Gaziantepspor | 4:0 | ||||
| 13. Round | 21/11/1998 | Gaziantepspor | - | Gençlerbirliği | 2:2 | ||||
| 15. Round | 05/12/1998 | Gaziantepspor | - | Samsunspor | 1:1 | ||||
| 16. Round | 12/12/1998 | Karabükspor | - | Gaziantepspor | 2:6 | ||||
| 17. Round | 19/12/1998 | Gaziantepspor | - | Galatasaray | 1:2 |
Turkey