The 2015 Estoril Open (also known as the Millennium Estoril Open for sponsorship purposes) was a tennis tournament played on outdoor clay courts. The 2015 tournament was the first edition of the Estoril Open (which replaced the Portugal Open), and part of the ATP World Tour 250 series of the 2015 ATP World Tour. The event took place at the Clube de Ténis do Estoril in Cascais, Portugal, from April 25 through May 3, 2015.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Spain | Feliciano López | 12 | 1 | |
| Kevin Anderson | 17 | 2 | ||
| Spain | ||||
 Argentina | Leonardo Mayer | 24 | 4 | |
 France | Richard Gasquet | 27 | 5 | |
| France | Jérémy Chardy | 32 | 6 | |
 Australia | Nick Kyrgios | 41 | 7 | |
 Luxembourg | Gilles Müller | 42 | 8 |
The following players received wildcards into the singles main draw:
The following players received entry from the qualifying draw:
The following player received entry as a lucky loser:
Marcos Baghdatis →replaced by Stéphane Robert Carlos Berlocq →replaced by Robin Haase Adrian Mannarino →replaced by Alejandro González Tommy Robredo →replaced by David Vega Hernández| Country | Player | Country | Player | Rank1 | Seed | |
|---|---|---|---|---|---|---|
| Spain | Marc López | Spain | David Marrero | 43 | 1 | |
| Treat Huey |  United States | Scott Lipsky | 92 | 2 | ||
 Poland | Mariusz Fyrstenberg |  Belarus | Max Mirnyi | 111 | 3 | |
| United States | Nicholas Monroe |  New Zealand | Artem Sitak | 116 | 4 |
The following pairs received wildcards into the doubles main draw:
See main article: 2015 Estoril Open – Singles.
Richard Gasquet def. Nick Kyrgios, 6–3, 6–2See main article: 2015 Estoril Open – Doubles.
Scott Lipsky def. Marc López / David Marrero, 6–1, 6–4
