McGrath is just one of two players who have previous experience of playing in the Junior World Championship. The other, Josh van der Flier, has been named in the back row.
Four players who were not involved in the Under-20 Six Nations earlier this year have earned places in the matchday squad - Leinster-capped winger Adam Byrne, centre Thomas Farrell and replacement forwards Edward Byrne and Daniel Leavy.
The versatile Rory Scannell, who played at centre and out-half during the Six Nations, moves to full-back with Farrell linking up in the centre with his Lansdowne club-mate Thomas Daly who scored 35 points in four Six Nations outings.
Provincial colleagues McGrath and Steve Crosbie continue their half-back partnership with Connacht youngster Adam Boland making his first start for the Ireland U-20s at tighthead prop.
Peadar Timmins, who started the season at blindside flanker, teams up with Ballynahinch clubman John Donnan in the second row, while Conor Joyce, Josh van der Flier and Ryan Murphy combine in the back row after starting together against France and Italy in March.
Mike Ruddock's charges share Pool B with Australia, Fiji and New Zealand. Ireland's pool matches will be broadcast live on TG4 along with the semi-finals and final games of the tournament in France.
IRELAND UNDER-20 Team & Replacements (v Australia Under-20s, 2013 IRB Junior World Championship Pool B, Stade de la Rabine, Vannes, Wednesday, June 5, kick-off 6.45pm local time/5.45pm Irish time):
15 - Rory Scannell (Dolphin/Munster)
14 - Adam Byrne (UCD/Leinster)
13 - Thomas Farrell (Lansdowne/Leinster)
12 - Thomas Daly (Lansdowne/Leinster)
11 - Rory Scholes (Belfast Harlequins/Ulster)
10 - Steve Crosbie (Old Belvedere/Leinster)
9 - Luke McGrath (UCD/Leinster) (capt)
1 - Peter Dooley (Lansdowne/Leinster)
2 - George McGuigan (Newcastle Falcons/Exile)
3 - Adam Boland (Lansdowne/Connacht)
4 - Peadar Timmins (UCD/Leinster)
5 - John Donnan (Ballynahinch/Ulster)
6 - Conor Joyce (Malone/Ulster)
7 - Josh van der Flier (UCD/Leinster)
8 - Ryan Murphy (Dolphin/Munster)
16 - Bryan Byrne (UCD/Leinster)
17 - Edward Byrne (UCD/Leinster)
18 - Ryan Furniss (Worcester Warriors/Exile)
19 - Sean McCarthy (Shannon/Munster)
20 - Daniel Leavy (UCD/Leinster)
21 - David Shanahan (Clontarf/Leinster)
22 - Mark Roche (Lansdowne/Connacht)
23 - Darragh Leader (Galwegians/Connacht)
IRELAND UNDER-20S' IRB JUNIOR WORLD CHAMPIONSHIP FIXTURES:
POOL B -
Wednesday, June 5: Ireland Under-20s v Australia Under-20s, Stade de la Rabine, Vannes, 6.45pm local time/5.45pm Irish time (live TG4/Sky Sports 3 red button/Sky Sports Xtra)
Sunday, June 9: Ireland Under-20s v Fiji Under-20s, Stade de la Rabine, Vannes, 6.45pm local time/5.45pm Irish time (live TG4/Sky Sports 4/HD4)
Thursday, June 13: New Zealand Under-20s v Ireland Under-20s, Stade de la Rabine, Vannes, 6.45pm local time/5.45pm Irish time (live TG4/Sky Sports 3 red button/Sky Sports Xtra)
Tuesday, June 18 and Sunday, June 23
Related Links -