| Date: | 30 July – 5 August |
| Edition: | 33rd (men) 4th (women) |
| Category: | ATP Challenger Tour ITF Women's Circuit |
| Location: | Segovia, Spain |
| Champms: |  Ugo Humbert |
| Champws: |  Liudmila Samsonova |
| Champmd: |  Andrés Artuñedo / David Pérez Sanz |
| Champwd: | Marina Bassols Ribera / Olga Parres Azcoitia |
The 2018 Open Castilla y León was a professional tennis tournament played on outdoor hard courts. It was the 33rd edition, for men, and 4th edition, for women, of the tournament and part of the 2018 ATP Challenger Tour and the 2018 ITF Women's Circuit. It took place in El Espinar, Segovia, Spain, between 30 July – 5 August 2018.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Ukraine | Sergiy Stakhovsky | 120 | 1 | |
| Spain | Adrián Menéndez Maceiras | 149 | 2 | |
 Italy | Luca Vanni | 191 | 3 | |
| Italy | Andrea Arnaboldi | 200 | 4 | |
| Scott Griekspoor | 210 | 5 | ||
| Daniel Brands | 217 | 6 | ||
| France | Ugo Humbert | 219 | 7 | |
The following players received wildcards into the singles main draw:
Andrés Artuñedo Alejandro Davidovich Fokina Jorge Hernando Ruano Miguel SemmlerThe following players received entry from the qualifying draw:
Yannick Jankovits
Karim-Mohamed Maamoun Alberto Romero de Ávila SeniseThe following player received entry as a lucky loser:
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
| Spain | Paula Badosa Gibert | 172 | 1 | |
| Spain | Olga Sáez Larra | 263 | 2 | |
 Turkey | Başak Eraydın | 270 | 3 | |
| France | Chloé Paquet | 293 | 4 | |
| France | Manon Arcangioli | 297 | 5 | |
| France | Tessah Andrianjafitrimo | 337 | 6 | |
| Russian Federation | Liudmila Samsonova | 346 | 7 | |
| Montserrat González | 349 | 8 |
The following players received wildcards into the singles main draw:
Ainhoa Atucha Gómez Lucía Cortez Llorca Ángela Díez Plágaro María Gutiérrez CarrascoThe following players received entry by special exempts:
The following players received entry from the qualifying draw:
Alba Carrillo Marín
Tamara Čurović
Mia Eklund Andrea Lázaro García Olga Parres AzcoitiaSee main article: 2018 Open Castilla y León – Men's singles.
Ugo Humbert def. Adrián Menéndez Maceiras 6–3, 6–4. Liudmila Samsonova def. Başak Eraydın, 6–2, 6–0See main article: 2018 Open Castilla y León – Men's doubles.
Andrés Artuñedo / David Pérez Sanz def. 
Matías Franco Descotte / João Monteiro 6–7(3–7), 6–3, [10–6]. Marina Bassols Ribera / Olga Parres Azcoitia def. Tamara Čurović / Başak Eraydın, 7–5, 6–4