Head Coach Sean Everitt hands starts to Darcy Graham, Magnus Bradbury and Freddy Douglas, while Liam McConnell is named among the replacements.
Everitt has selected an extended 26-man squad as the capital club continue their preparations for the 2026/27 season, which gets underway against Ulster in Belfast next weekend.
On the selection, Everitt said: “It’s exciting as we get closer to the competitive action starting next week, and tomorrow night will be an important building block as we build towards our season opener against Ulster.
“We’ve had a really good training week, and an extended squad of players are looking forward to getting more minutes under their belt against a strong Quins side here in London.”
Scotland international Harry Paterson starts at full-back, with Geordie Gwynn shifting from the centres to partner Graham on the wing.
Mosese Tuipulotu takes the 12 jersey, joined by Matt Currie in the capital midfield.
James Grayson continues at fly-half, with Hector Paterson partnering him at scrum-half.
Summer arrival Alec Hepburn starts at loosehead, with former England international Paul Hill at tighthead and Jerry Blyth-Lafferty at hooker.
Glen Young starts at lock to face his former side, forming the engine room alongside Callum Hunter-Hill.
In the back row, Bradbury and Douglas are joined by blindside flanker Tom Dodd, who was named Scottish Building Society Player of the Match against Ulster.
On the bench, Edinburgh welcome back Ben Muncaster from injury, while Scotland U20 internationals Henry Kesterton and Jack Utterson are also in line for senior minutes.
Edinburgh Rugby team to face Harlequins in a pre-season friendly at Twickenham Stoop
Friday 18 September (kick-off 7.45pm) – live on the official Harlequins app
15. Harry Paterson
14. Darcy Graham
13. Matt Currie
12. Mosese Tuipulotu
11. Geordie Gwynn
10. James Grayson
9. Hector Patterson
1. Alec Hepburn
2. Jerry Blyth-Lafferty
3. Paul Hill
4. Callum Hunter-Hill
5. Glen Young
6. Tom Dodd
7. Freddy Douglas
8. Magnus Bradbury
Replacements
16. Jack Utterson
17. James Whitcombe
18. Ollie Blyth-Lafferty
19. Euan McVie
20. Liam McConnell
21. Ben Muncaster
22. Tom Currie
23. Conor McAlpine
24. Ross Thompson
25. Henry Kesterton
26. Piers O’Conor
Unavailable: Patrick Harrison (back), Dylan Richardson (groin), Duhan van der Merwe (ankle), Luke Crosbie (hamstring), Grant Gilchrist (bicep), Rhys Litterick (achilles), Ben Vellacott (shoulder), Marshall Sykes (shoulder), Connor Boyle (knee), Jack Brown (knee), Harris Morris (head), Wes Goosen (hamstring), Malelili Satala (ankle), D’arcy Rae (calf).