1989–90 NSL Cup

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.

Teams
The NSL Cup was a knockout competition with 14 teams taking part all trying to reach the Final in April 1990. The competition consisted of the 14 teams from the National Soccer League.

First round
APIA Leichhardt and Blacktown City had a bye for the First round.