# 1991 Campionati Internazionali di San Marino – Singles

Guillermo Pérez Roldán successfully defended his title, by defeating Frédéric Fontang 6–3, 6–1 in the final.

## Seeds

* Guillermo Pérez Roldán (champion)
* Jordi Arrese (second round)
* Nicklas Kulti (quarterfinals)
* Franco Davín (quarterfinals)
* Renzo Furlan (semifinals)
* Roberto Azar (semifinals)
* Nuno Marques (second round)
* José Francisco Altur (first round)

## Draw
### Key

* Q = Qualifier
* WC = Wild card
* LL = Lucky loser
* Alt = Alternate
* SE = Special exempt
* PR = Protected ranking
* ITF = ITF entry
* JE = Junior exempt
* w/o = Walkover
* r = Retired
* d = Defaulted
* SR = Special ranking

### Finals

| Semifinals | Semifinals | Semifinals | Semifinals | Final | Final | Final | Final |
| 1 | Guillermo Pérez Roldán | 6 | 6 | | | | |
| 5 | Renzo Furlan | 2 | 2 | | | | |
| 5 | Renzo Furlan | 2 | 2 | 1 | Guillermo Pérez Roldán | 6 | 6 |
| | | | | | Frédéric Fontang | 3 | 1 |
| 6 | Roberto Azar | 2 | 2 | | Frédéric Fontang | 3 | 1 |
| | Frédéric Fontang | 6 | 6 | | | | |

### Top half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 1 | G Pérez Roldán | 6 | 6 | | | | | | | | | | | | | | | |
| | D Pérez | 0 | 1 | | 1 | G Pérez Roldán | 2 | 6 | 7$^7$ | | | | | | | | | |
| Q | M Oosting | 6 | 6 | | Q | M Oosting | 6 | 0 | 6$^4$ | | | | | | | | | |
| WC | O Rahnasto | 0 | 1 | | | | | | | 1 | G Pérez Roldán | 5 | 6 | 6 | | | | |
| | F Luna | 2 | 1 | | | | | | | | C Costa | 7 | 2 | 1 | | | | |
| | L Němeček | 6 | 6 | | | L Němeček | 2 | 2 | | | | | | | | | | |
| | C Costa | 6 | 7$^7$ | | | C Costa | 6 | 6 | | | | | | | | | | |
| 8 | JF Altur | 4 | 6$^5$ | | | | | | | | | | | | 1 | G Pérez Roldán | 6 | 6 |
| 4 | F Davín | 6 | 6 | | | | | | | | | | | | 5 | R Furlan | 2 | 2 |
| Q | M Ardinghi | 1 | 1 | | 4 | F Davín | 7$^7$ | 7 | | | | | | | | | | |
| | J Cunha e Silva | 6$^5$ | 3 | | | P Canè | 6$^2$ | 5 | | | | | | | | | | |
| | P Canè | 7$^7$ | 6 | | | | | | | 4 | F Davín | 2 | 3 | | | | | |
| | P Pambianco | 7$^7$ | 4 | 6 | | | | | | 5 | R Furlan | 6 | 6 | | | | | |
| | S Doseděl | 6$^2$ | 6 | 2 | | P Pambianco | 4 | 2 | | | | | | | | | | |
| | C Miniussi | 3 | 1 | | 5 | R Furlan | 6 | 6 | | | | | | | | | | |
| 5 | R Furlan | 6 | 6 | | | | | | | | | | | | | | | |

### Bottom half

| First round | First round | First round | First round | First round | Second round | Second round | Second round | Second round | Second round | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Quarterfinals | Semifinals | Semifinals | Semifinals | Semifinals |
| 6 | R Azar | 6 | 6 | | | | | | | | | | | | | | | |
| | M Cierro | 3 | 1 | | 6 | R Azar | 6 | 2 | 6 | | | | | | | | | |
| | D Orsanic | 6 | 6 | | | D Orsanic | 4 | 6 | 4 | | | | | | | | | |
| | V Roubíček | 2 | 2 | | | | | | | 6 | R Azar | 3 | 7 | 6 | | | | |
| | M Górriz | 6 | 6 | | | | | | | 3/WC | N Kulti | 6 | 5 | 4 | | | | |
| | T Anzari | 4 | 2 | | | M Górriz | 3 | 2 | | | | | | | | | | |
| Q | J Sobel | 1 | 1 | | 3/WC | N Kulti | 6 | 6 | | | | | | | | | | |
| 3/WC | N Kulti | 6 | 6 | | | | | | | | | | | | 6 | R Azar | 2 | 2 |
| 7 | N Marques | 6 | 7 | | | | | | | | | | | | | F Fontang | 6 | 6 |
| | M Ingaramo | 3 | 5 | | 7 | N Marques | 3 | 3 | | | | | | | | | | |
| LL | M Visconti | 6$^3$ | 3 | | WC | C Mezzadri | 6 | 6 | | | | | | | | | | |
| WC | C Mezzadri | 7$^7$ | 6 | | | | | | | WC | C Mezzadri | 4 | 0 | | | | | |
| | F Fontang | 6 | 6 | | | | | | | | F Fontang | 6 | 6 | | | | | |
| Q | MI Năstase | 3 | 4 | | | F Fontang | 6 | 6 | | | | | | | | | | |
| | P Rebolledo | 7 | 2 | 2 | 2 | J Arrese | 3 | 0 | | | | | | | | | | |
| 2 | J Arrese | 5 | 6 | 6 | | | | | | | | | | | | | | |