1989–90 ACB season

The competition format was the same as the previous season.

FC Barcelona won their 4th ACB title, and their 7th overall.

It was their 4th ACB title in a row.

Tenerife Nº 1 and Gran Canaria were relegated.

(I-1) CAI Zaragoza vs. (III-3) Cajacanarias CAI Zaragoza win the series 3-0 and qualified to play in the A-1 the next season (I-2) Mayoral Maristas vs. (II-3) Caja San Fernando Caja San Fernando win the series 3-1 and qualified to play in the A-1 the next season (III-1) Pamesa Valencia vs. (II-2) Cajabilbao Pamesa Valencia win the series 3-0 and qualified to play in the A-1 the next season (II-1) Huesca Magia vs. (III-2) BBV Villalba BBV Villalba win the series 3-1 and qualified to play in the A-1 the next season