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.[1]
South Melbourne defeated Sydney Olympic 4–1 in the final to win their first NSL Cup title.[2]
Teams
The NSL Cup was a knockout competition with 14 teams taking part all trying to reach the Final in April 1990.[3] The competition consisted of the 14 teams from the National Soccer League.