1989–90 NSL Cup
| National Soccer League Cup | |
|---|---|
| Tournament details | |
| Country | Australia |
| Dates | 7 February – 25 April 1990 |
| Teams | 14 |
| Final positions | |
| Champions | South Melbourne (1st title) |
| Runners-up | Sydney Olympic |
| Tournament statistics | |
| Matches played | 13 |
| Goals scored | 47 (3.62 per match) |
| Attendance | 44,073 (3,390 per match) |
| Top goal scorer(s) | Abbas Saad Kimon Taliadoros Paul Trimboli (3 each) |
The 1989–90 NSL Cup was the 14th edition of the NSL Cup, which was the main national association football knockout cup competition in Australia.
Adelaide City were the defending champions, having defeated Sydney Olympic to win their second title in the previous year's final, but they were eliminated in the semi-finals by eventual winners South Melbourne.
South Melbourne defeated Sydney Olympic 4–1 in the final to win their first NSL Cup title.