The 2011 Estoril Open was a tennis tournament played on outdoor clay courts. It was the 22nd edition of the Estoril Open for the men (the 15th for the women), and was part of the ATP World Tour 250 series of the 2011 ATP World Tour, and of the International-level tournaments of the 2011 WTA Tour. Both the men's and the women's events took place at the Estádio Nacional in Oeiras, Portugal, from 23 April through 1 May 2011.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Sweden | Robin Söderling | 5 | 1 | |
 Spain | Fernando Verdasco | 12 | 2 | |
 France | Jo-Wilfried Tsonga | 18 | 3 | |
| France | Gilles Simon | 22 | 4 | |
 Canada | Milos Raonic | 28 | 5 | |
 Brazil | Thomaz Bellucci | 32 | 6 | |
| Kevin Anderson | 35 | 7 | ||
 Argentina | Juan Martín del Potro | 46 | 8 |
The following players received wildcards into the main draw:
The following players received entry from the qualifying draw:
See main article: 2011 Estoril Open – Men's singles qualifying.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Russian Federation | Alisa Kleybanova | 25 | 1 | |
 Australia | Jarmila Gajdošová | 30 | 2 | |
 Czech Republic | Klára Zakopalová | 35 | 3 | |
| Anastasija Sevastova | 38 | 4 | ||
 United States | Bethanie Mattek-Sands | 41 | 5 | |
| Russian Federation | Elena Vesnina | 45 | 6 | |
 China | Zheng Jie | 51 | 7 | |
 Hungary | Gréta Arn | 52 | 8 |
The following players received wildcards into the main draw:
The following players received entry from the qualifying draw:
See main article: 2011 Estoril Open – Women's singles qualifying.
See main article: 2011 Estoril Open – Men's singles. Juan Martín del Potro defeated Fernando Verdasco, 6–2, 6–2
See main article: 2011 Estoril Open – Women's singles. Anabel Medina Garrigues defeated Kristina Barrois, 6–1, 6–2.
See main article: 2011 Estoril Open – Men's doubles. Eric Butorac / Jean-Julien Rojer defeated Marc López / David Marrero, 6–3, 6–4.
See main article: 2011 Estoril Open – Women's doubles. Alisa Kleybanova / 
Galina Voskoboeva defeated Eleni Daniilidou / Michaëlla Krajicek, 6–4, 6–2.
