The 1991 US Open was a tennis tournament played on outdoor hard courts at the USTA National Tennis Center in New York City in New York in the United States.

It was the 111th edition of the US Open and was held from August 26 to September 8, 1991.

Stefan Edberg defeated Jim Courier 6–2, 6–4, 6–0 Monica Seles defeated Martina Navratilova 7–6(7–1), 6–1 John Fitzgerald / Anders Järryd defeated Scott Davis / David Pate 6–3, 3–6, 6–3, 6–3 Pam Shriver / Natasha Zvereva defeated Jana Novotná / Larisa Savchenko 6–4, 4–6, 7–6(7–5) Manon Bollegraf / Tom Nijssen defeated Arantxa Sánchez Vicario / Emilio Sánchez 6–2, 7–6(7–2) Leander Paes defeated Karim Alami 6–4, 6–4 Karina Habšudová defeated Anne Mall 6–1, 6–3 Karim Alami / John-Laffnie de Jager defeated Michael Joyce / Vince Spadea 6–4, 6–7, 6–1 Kristin Godridge / Nicole Pratt defeated Åsa Carlsson / Cătălina Cristea 7–6, 7–5