1990–91 NSL Cup
| National Soccer League Cup | |
|---|---|
| Tournament details | |
| Country | Australia |
| Dates | 21 November 1990 – 7 April 1991 |
| Teams | 14 |
| Final positions | |
| Champions | Melita Eagles (1st title) |
| Runners-up | Preston Makedonia |
| Tournament statistics | |
| Matches played | 13 |
| Goals scored | 29 (2.23 per match) |
| Attendance | 37,506 (2,885 per match) |
| Top goal scorer(s) | Greg Brown (3) |
The 1990–91 NSL Cup was the 15th edition of the NSL Cup, which was the main national association football knockout cup competition in Australia.
South Melbourne were the defending champions, having defeated Sydney Olympic to win their first title in the previous year's final, but they were eliminated in the semi-finals by eventual winners Melita Eagles.
Melita Eagles defeated Preston Makedonia 1–0 in the final to win their first NSL Cup title.