| 1989 WTA Tier I Series | |
| Duration: | March 20 – May 15 |
| Tournaments: | 2 |
| Most Tournament Titles: | Gabriela Sabatini Steffi Graf (1) |
| Most Tournament Finals: | Gabriela Sabatini (2) |
| Previous: | 1988 |
| Next: | 1990 |
See main article: article and 1989 WTA Tour.
The table below shows the 1989 WTA Tier I Series schedule.
| Tournament | Surface | Week | Winner | Finalist | Semi finalists | Quarter finalists |
|---|---|---|---|---|---|---|
| Key Biscayne | Hard | March 20 |  Gabriela Sabatini 6–1, 4–6, 6–2 | Helena Suková  Zina Garrison Jackson |  Isabelle Demongeot  Raffaella Reggi-Concato Jana Novotná  Helen Kelesi | |
| Berlin | Clay | May 15 | Steffi Graf 6–3, 6–1 | Gabriela Sabatini | Isabel Cueto Helen Kelesi | |