The 2015 Open Castilla y León was a professional tennis tournament played on hard courts. It was the 30th edition of the tournament which was part of the 2015 ATP Challenger Tour. It took place in Segovia, Spain between 3 and 9 August 2015.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Spain | Marcel Granollers | 73 | 1 | |
| Dustin Brown | 81 | 2 | ||
| Matthias Bachinger | 110 | 3 | ||
| Spain | Adrián Menéndez Maceiras | 117 | 4 | |
 Bosnia and Herzegovina | Mirza Bašić | 153 | 5 | |
| Peter Gojowczyk | 155 | 6 | ||
 France | Vincent Millot | 162 | 7 | |
 Russian Federation | Alexander Kudryavtsev | 166 | 8 |
The following players received wildcards into the singles main draw:
Francisco Blanco Paris
Chung Yun-seong Marcel Granollers Jorge RuanoThe following player entered using a protected ranking:
The following players received entry from the qualifying draw:
Sébastien Boltz
Egor Gerasimov Georgi RumenovThe following players received entry by a lucky loser spot:
See main article: 2015 Open Castilla y León – Singles.
Evgeny Donskoy def. Marco Chiudinelli 7–6(7–2), 6–3See main article: 2015 Open Castilla y León – Doubles.
Alexander Kudryavtsev / 
Denys Molchanov def. Aliaksandr Bury / 
Andreas Siljeström 6–2, 6–4