Donohue's squad will face Latvia in Castlebar, Faroe Islands in Westport and Luxembourg in Ballina in his side's first fixtures of the season.
Among the call-ups are Westport trio Conor Walsh Daniel Kelly, and Adam Nugent - all of Mayo SL.
The Ireland Under-15 Head Coach said: "In the three to four years I have been doing the job this has been the most difficult squad to select in terms of the amount of good quality we have out there. The standard is very high for this age group and I was splitting hairs picking between certain players.
"We've three boys from Mayo [Walsh, Kelly, Nugent] who have made the squad and will represent their country. Make no mistake they are here on merit and it's a great chance for them to play in front of people from their county. It's not only a great opportunity for them but also for the squad to showcase their talents."
Donohue said the matches will present different challenges for his side. He added: "Latvia will be a little bit older than us as their players are born ’04 where as our players are ’05. That will be a big test both physically and mentally and a question of whether our players can maintain the standard throughout the 80 minutes.
"Luxembourg and Faroe Islands are a different proposition, they train with club teams due to the size of their countries and will surprise people. They will prove there are no easy games at international football, that’s for sure."
Republic of Ireland Under-15 squad
Goalkeepers: Shay O’Leary (Shamrock Rovers), Conor Walsh (Mayo SL)
Defenders: Cathal Heffernan (Cork City), Daniel Kelly (Mayo SL), Finn Cowper Gray (Klub Kildare), Luke O’Brien (SJB Academy / Bray Wanderers), Sam Curtis (Shamrock Rovers), Trisden Wholey Hughes (Shamrock Rovers)
Midfielders: Caden McLoughlin (Malaga CF), Cian Barrett (Shamrock Rovers), Eanna Fitzgerald (Cork City), Giddeon Tetteh (Shamrock Rovers), James McManus (St Kevin’s Boys / Bohemians), Joe O’Brien Whitmarsh (Cork City), Justin Ferizaj (Shamrock Rovers), Kevin Zefi (Shamrock Rovers)
Forwards: Adam Murphy (Belvedere FC), Adam Nugent (Mayo SL), Alex Nolan (Cabinteely), Mark Tansey (SJB Academy / Bray Wanderers).
Fixtures
October 17 - Ireland v Latvia, KO 3pm, Solar 21 Park Castlebar
October 19 - Ireland v Faroe Islands, KO 3pm, Westport United, Westport
October 21 - Ireland v Luxembourg, KO 11am, Ballina Town FC, Ballina