| 1991 Estoril Open | |
|---|---|
| Date | 1–8 April |
| Edition | 2nd |
| Category | World Series |
| Draw | 32S / 16D |
| Prize money | $337,500 |
| Surface | Clay / outdoor |
| Location | Oeiras, Portugal |
| Champions | |
| Singles | |
 Sergi Bruguera[1] | |
| Doubles | |
 Paul Haarhuis / Mark Koevermans[2] | |
The 1991 Estoril Open was a tennis tournament played on outdoor clay courts. This event was the 2nd edition of the Estoril Open, included in the 1991 ATP Tour World Series. The event took place at the Estoril Court Central, in Oeiras, Portugal, from April 1 through April 8, 1991.
