The 1991 OTB International Open was a combined men's and women's tennis tournament played on outdoor hard courts that was part of the World Series of the 1991 ATP Tour.

It was the fifth edition of the tournament and was held in Schenectady, New York in the United States from August 19 through August 26, 1991.

Michael Stich and Brenda Schultz won the singles titles.

[3] Michael Stich defeated Emilio Sánchez 6–2, 6–4 Brenda Schultz defeated Alexia Dechaume 7–6(7–5), 6–2 Javier Sánchez / Todd Woodbridge defeated Andrés Gómez / Emilio Sánchez 3–6, 7–6, 7–6 Rachel McQuillan / Claudia Porwik defeated Nicole Arendt / Shannan McCarthy 6–2, 6–4