The 1991 Internazionali Cassa di Risparmio, also known as the Bologna Open, was a men's tennis tournament played on outdoor clay courts at the Cierrebi Club in Bologna in Italy and was part of the World Series of the 1991 ATP Tour.

It was the seventh edition of the tournament and was held from 20 May until 26 May 1991.

Unseeded Paolo Canè, who entered the main draw on a wildcard, won the singles title.

[3] Paolo Canè defeated Jan Gunnarsson 5–7, 6–3, 7–5 Luke Jensen / Laurie Warder defeated Luiz Mattar / Jaime Oncins 6–4, 7–6