The 1991 Puerto Rico Open was a women's tennis tournament played on outdoor hard courts at the Hyatt Regency Cerromar Hotel in San Juan in Puerto Rico that was part of the Tier IV category of the 1991 WTA Tour.

It was the sixth edition of the tournament and was held from October 21 through October 27, 1991.

Second-seeded Julie Halard won the singles title and earned $27,000 first-prize money.

[1][2] Julie Halard defeated Amanda Coetzer 7–5, 7–5 Rika Hiraki / Florencia Labat defeated Sabine Appelmans / Camille Benjamin 6–3, 6–3