1989 OTB Open – Women's singles

Gretchen Magers was the defending champion but lost in the semifinals to Laura Gildemeister.

Gildemeister won in the final 6–4, 6–3 against Marianne Werdel.

Seeds
A champion seed is indicated in bold text while text in italics indicates the round in which that seed was eliminated. The top eight seeds received a bye to the second round.


 * 1) 🇺🇸 Gretchen Magers (semifinals)
 * 2) 🇺🇸 Halle Cioffi (second round)
 * 3) 🇺🇸 Ann Grossman (third round)
 * 4) 🇺🇸 Betsy Nagelsen (second round)
 * 5) 🇺🇸 Ann Henricksson (quarterfinals)
 * 6) 🇺🇸 Carrie Cunningham (second round)
 * 7) 🇺🇸 Beverly Bowes (third round)
 * 8) 🇵🇪 Laura Gildemeister (champion)
 * 9) 🇺🇸 Louise Allen (third round)
 * 10)  Eva Krapl (second round)
 * 11) 🇺🇸 Stacey Martin (quarterfinals)
 * 12) 🇺🇸 Beth Herr (third round)
 * 13) 🇺🇸 Hu Na (third round)
 * 14) 🇺🇸 Marianne Werdel (final)
 * 15) 🇺🇸 Kim Kessaris (second round)
 * 16) 🇦🇺 Michelle Jaggard (second round)