| 2003-04 ACB season | |
| League: | Liga ACB |
| Sport: | Basketball |
| No Of Teams: | 18 |
| No Of Games: | 340 |
| Tv: | Televisión Española |
| Season: | Regular Season |
| Season Champs: | TAU Cerámica |
| Mvp: |  Andrés Nocioni (TAU Cerámica) |
| Mvp Link: | ACB Most Valuable Player Award |
| Playoffs: | Playoffs |
| Finals: | ACB Finals |
| Finals Champ: | FC Barcelona |
| Finals-Runner-Up: | FC Barcelona |
| Finals Mvp: | Dejan Bodiroga (FC Barcelona) |
| Finals Mvp Link: | ACB Finals Most Valuable Player Award |
| Seasonslistnames: | ACB |
| Prevseason Link: | 2002–03 ACB season |
| Prevseason Year: | 2002–03 |
| Nextseason Link: | 2004–05 ACB season |
| Nextseason Year: | 2004–05 |
The 2003–04 ACB season was the 21st season of the Liga ACB.
| Pos | Team | GP | GW | GL | PF | PC | Qualification or relegation |
|---|---|---|---|---|---|---|---|
| 1 | 34 | 28 | 6 | 2964 | 2668 | Qualified for Playoffs | |
| 2 | 34 | 23 | 11 | 2606 | 2462 | ||
| 3 | 34 | 23 | 11 | 2841 | 2659 | ||
| 4 | 34 | 20 | 14 | 2750 | 2642 | ||
| 5 | 34 | 20 | 14 | 2846 | 2727 | ||
| 6 | 34 | 20 | 14 | 2621 | 2623 | ||
| 7 | 34 | 17 | 17 | 2551 | 2529 | ||
| 8 | 34 | 16 | 18 | 2829 | 2759 | ||
| 9 | 34 | 16 | 18 | 2707 | 2697 | ||
| 10 | 34 | 16 | 18 | 2651 | 2715 | ||
| 11 | 34 | 16 | 18 | 2798 | 2844 | ||
| 12 | 34 | 15 | 19 | 2708 | 2684 | ||
| 13 | 34 | 15 | 19 | 2735 | 2785 | ||
| 14 | 34 | 14 | 20 | 2558 | 2633 | ||
| 15 | 34 | 14 | 20 | 2714 | 2818 | ||
| 16 | 34 | 13 | 21 | 2673 | 2790 | ||
| 17 | 34 | 13 | 21 | 2704 | 2932 | Relegated to LEB | |
| 18 | 34 | 7 | 27 | 2565 | 2854 |
| Play-Offs | Direct relegation |