| 1998-99 ACB season | |
| League: | Liga ACB |
| Sport: | Basketball |
| No Of Teams: | 18 |
| No Of Games: | 340 |
| Tv: | Televisión Española |
| Season: | Regular Season |
| Season Champs: | FC Barcelona |
| Mvp: |  Tanoka Beard (Real Madrid) |
| Mvp Link: | ACB Most Valuable Player Award |
| Playoffs: | Playoffs |
| Finals: | ACB Finals |
| Finals Champ: | FC Barcelona |
| Finals-Runner-Up: | Caja San Fernando |
| Finals Mvp: | Derrick Alston (FC Barcelona) |
| Finals Mvp Link: | ACB Finals Most Valuable Player Award |
| Seasonslistnames: | ACB |
| Prevseason Link: | 1997–98 ACB season |
| Prevseason Year: | 1997–98 |
| Nextseason Link: | 1999–2000 ACB season |
| Nextseason Year: | 1999–00 |
The 1998-1999 ACB season was the 17th season of the Liga ACB.
| Pos | Equipo | J | G | P | PF | PC | Qualification or relegation |
|---|---|---|---|---|---|---|---|
| 1 | FC Barcelona | 34 | 26 | 8 | 2885 | 2543 | Qualification to playoffs |
| 2 | Real Madrid | 34 | 26 | 8 | 2768 | 2524 | |
| 3 | Caja San Fernando | 34 | 25 | 9 | 2488 | 2366 | |
| 4 | TAU Cerámica | 34 | 24 | 10 | 2712 | 2576 | |
| 5 | Adecco Estudiantes | 34 | 21 | 13 | 2791 | 2652 | |
| 6 | Pamesa Cerámica | 34 | 18 | 16 | 2600 | 2565 | |
| 7 | Baloncesto Fuenlabrada | 34 | 18 | 16 | 2758 | 2719 | |
| 8 | Girona Gavis | 34 | 18 | 16 | 2696 | 2692 | |
| 9 | Unicaja Málaga | 34 | 18 | 16 | 2577 | 2532 | |
| 10 | Pinturas Bruguer Badalona | 34 | 18 | 16 | 2666 | 2565 | |
| 11 | TDK Manresa | 34 | 16 | 18 | 2532 | 2545 | |
| 12 | Cáceres CB | 34 | 14 | 20 | 2566 | 2613 | |
| 13 | Fórum Valladolid | 34 | 13 | 21 | 2574 | 2625 | |
| 14 | CB Gran Canaria | 34 | 13 | 21 | 2506 | 2585 | |
| 15 | Lobos Caja Cantabria | 34 | 13 | 21 | 2724 | 2891 | |
| 16 | León Caja España | 34 | 13 | 21 | 2478 | 2699 | |
| 17 | Covirán Cervezas Alhambra | 34 | 8 | 26 | 2436 | 2730 | Relegation to LEB |
| 18 | Recreativos Orenes Murcia | 34 | 4 | 30 | 2517 | 2852 |