The 1991 Volvo San Marino Open was a women's tennis tournament played on outdoor clay courts at the Centro Sportivo Tennis in the City of San Marino, San Marino that was part of the Tier V category of the 1991 WTA Tour.

It was the inaugural edition of the WTA San Marino and was held from 15 July until 21 July 1991.

Second-seeded Katia Piccolini won the singles title and earned $13,500 first-prize money.

[1][2] Katia Piccolini defeated Silvia Farina 6–2, 6–3 Kerry-Anne Guse / Akemi Nishiya defeated Laura Garrone / Mercedes Paz 6–0, 6–3