The 1991 Manchester Open was the second edition of the Manchester Open men's tennis tournament and was played outdoor grass court at the Northern Lawn Tennis Club in Manchester, United Kingdom.

The tournament was part of the ATP World Series of the 1991 ATP Tour and was held from 17 June until 24 June 1991.

Second-seeded Goran Ivanišević won the singles title.

[3] Goran Ivanišević defeated Pete Sampras 6–4, 6–4 Omar Camporese / Goran Ivanišević defeated Nick Brown / Andrew Castle 6–4, 6–3