| Doubles | |
|---|---|
| 2018 Open Harmonie mutuelle | |
| Champions |  Sander Arends  Tristan-Samuel Weissborn |
| Runners-up |  Luke Bambridge Joe Salisbury |
| Final score | 4–6, 6–1, [10–7] |
Andre Begemann and Frederik Nielsen were the defending champions but chose not to defend their title.
Sander Arends and Tristan-Samuel Weissborn won the title after defeating Luke Bambridge and Joe Salisbury 4–6, 6–1, [10–7] in the final.
Hugo Nys / Ken Skupski (semifinals)
Jeevan Nedunchezhiyan / Purav Raja (first round) Sander Arends / Tristan-Samuel Weissborn (champions) Luke Bambridge / Joe Salisbury (final)| First round | Quarterfinals | Semifinals | Final | ||||||||||||||||||||||||
| 1 | H Nys K Skupski | 6 | 6 | ||||||||||||||||||||||||
 B Mousley  G Oliveira | 4 | 4 | 1 | H Nys K Skupski | 7 | 7 | |||||||||||||||||||||
 A Mies O Otte | 77 | 6 | A Mies O Otte | 5 | 5 | ||||||||||||||||||||||
 N Lammons A Lawson | 65 | 4 | 1 | H Nys K Skupski | 62 | 5 | |||||||||||||||||||||
| 4 | L Bambridge J Salisbury | 6 | 6 | 4 | L Bambridge J Salisbury | 77 | 7 | ||||||||||||||||||||
T Lamasine  S Stakhovsky | 4 | 4 | 4 | L Bambridge J Salisbury | 6 | 6 | |||||||||||||||||||||
| WC | D Descloix C Lestienne | 6 | 6 | WC | D Descloix C Lestienne | 4 | 1 | ||||||||||||||||||||
| WC | G Barrère D Guez | 3 | 4 | 4 | L Bambridge J Salisbury | 6 | 1 | [7] | |||||||||||||||||||
| S Clayton D Pel | 6 | 6 | 3 | S Arends T-S Weissborn | 4 | 6 | [10] | ||||||||||||||||||||
| WC | E Furness M Guinard | 4 | 3 | S Clayton D Pel | 0 | 4 | |||||||||||||||||||||
 Z Kolář  L Margaroli | 0 | 3 | 3 | S Arends T-S Weissborn | 6 | 6 | |||||||||||||||||||||
| 3 | S Arends T-S Weissborn | 6 | 6 | 3 | S Arends T-S Weissborn | 6 | 6 | ||||||||||||||||||||
 R Berankis  M Sabanov | 3 | 3 |  Sa Ratiwatana So Ratiwatana | 4 | 3 | ||||||||||||||||||||||
 M Safwat  J Zopp | 6 | 6 | M Safwat J Zopp | 1 | 1 | ||||||||||||||||||||||
| Sa Ratiwatana So Ratiwatana | 77 | 3 | [10] | Sa Ratiwatana So Ratiwatana | 6 | 6 | |||||||||||||||||||||
| 2 | J Nedunchezhiyan P Raja | 65 | 6 | [8] | |||||||||||||||||||||||
Andrej Martin and Hans Podlipnik were the defending champions but chose to participate with different partners. Martin chose to participate with Tomasz Bednarek, while Podlipnik chose to partner with Lukáš Dlouhý. Martin and Podlipnik faced each other in the semifinals, with Podlipnik advancing to the final. Podlipnik failed to defend his title, losing to Sander Arends and Tristan-Samuel Weissborn 7–6(10–8), 6–7(4–7), [10–5] in the final.
Mateusz Kowalczyk and Igor Zelenay were the defending champions but chose to participate with different partners. Kowalczyk partnered Tomasz Bednarek while Zelenay partnered Rameez Junaid. Both failed to defend their title, with Kowalczyk losing to Zelenay in the first round and Zelenay losing to Sander Arends and Tristan-Samuel Weissborn in the quarterfinals.
Wesley Koolhof and Matwé Middelkoop were the defending champions but chose not to defend their title.
Sander Arends and Tristan-Samuel Weissborn were the defending champions but only Weissborn chose to defend his title, partnering Dino Marcan. Weissborn lost in the quarterfinals to Hugo Nys and Max Schnur.
Mikhail Elgin and Alexander Kudryavtsev were the defending champions but chose not to defend their title.
Hans Podlipnik-Castillo and Andrei Vasilevski were the defending champions but chose not to defend their title.
Evgeny Donskoy and Mikhail Elgin were the defending champions but chose not to defend their title.
The 2018 Open Harmonie mutuelle was a professional tennis tournament played on hard courts. It was the fifteenth edition of the tournament which was part of the 2018 ATP Challenger Tour. It took place in Saint-Brieuc, France between 26 March and 1 April 2018.
Pierre-Hugues Herbert and Adil Shamasdin were the defending champions but only Shamasdin chose to defend his title, partnering Sander Arends. Shamasdin lost in the quarterfinals to Dennis Novak and Tristan-Samuel Weissborn.
Guillermo Durán and Andrés Molteni were the defending champions but chose not to defend his title.
Romain Arneodo and Tristan-Samuel Weissborn were the defending champions but only Weissborn chose to defend his title, partnering Sander Arends. Weissborn lost in the first round to Jürgen Melzer and Filip Polášek.
Sander Gillé and Joran Vliegen were the defending champions but chose not to defend their title.
Sander Arends and Tristan-Samuel Weissborn were the defending champions but lost in the semifinals to Jonathan Eysseric and Antonio Šančić.
Matthew Ebden and Andrew Whittington were the defending champions but chose not to defend their title.
Aliaksandr Bury and Lloyd Harris were the defending champions but chose not to defend their title.
Gong Maoxin and Zhang Ze were the defending champions but chose not to defend their title.
Toshihide Matsui and Frederik Nielsen were the defending champions but only Matsui chose to defend his title, partnering Ričardas Berankis. Matsui lost in the first round to Nam Ji-sung and Song Min-kyu.
Hsieh Cheng-peng and Christopher Rungkat were the defending champions and successfully defended their title, defeating Toshihide Matsui and Vishnu Vardhan 7–6(9–7), 6–1 in the final.
Luke Bambridge and Jonny O'Mara were the defending champions but only O'Mara chose to defend his title, partnering Ken Skupski. O'Mara lost in the semifinals to Hans Podlipnik Castillo and Tristan-Samuel Weissborn.
Sander Arends and Tristan-Samuel Weissborn were the defending champions but only Weissborn chose to defend his title, partnering Antonio Šančić. Weissborn successfully defended his title after defeating Teymuraz Gabashvili and Lukáš Lacko 7–5, 6–7(5–7), [10–7] in the final.