The 2005 Under-21 Rugby World Championship took place in Argentina between 9 June and 25 June 2005. The 2005 championship was the fourth contested. This championship saw South Africa win the final over Australia 24–20.
The following 12 teams participated in the 2005 Under-21 Rugby World Championship.
The 12 teams were split into four groups of three teams. After all pool matches teams are ranked by total match points. Four group winners qualify for the semi-finals and bottom eight enter play-offs for positions 5–8 and 9–12.
9 June, New Zealand 60 - 15 Wales Liceo RC, Mendoza
9 June, Scotland 22 - 28 Australia Chacras RC, Mendoza
9 June, Argentina 65 - 7 Canada Liceo RC, Mendoza
13 June, New Zealand 92 - 7 Canada Mendoza RC, Mendoza
13 June, Scotland 8 - 24 Wales Maristas RC, Mendoza
13 June, Argentina 20 - 25 Australia Mendoza RC, Mendoza
17 June, New Zealand 43 - 46 Australia Chacras RC, Mendoza
17 June, Scotland 52 - 20 Canada Liceo RC, Mendoza
17 June, Argentina 36 - 31 Wales Chacras RC, Mendoza
9 June, || England || 52–22 || Samoa || Maristas RC, Mendoza
9 June, || Italy || 3–83 || South Africa || Maristas RC, Mendoza
9 June, Ireland 23 - 31 France Chacras RC, Mendoza
13 June, England 16 - 34 South Africa Liceo RC, Mendoza
13 June, Ireland 29 - 21 Samoa Maristas RC, Mendoza
13 June, Italy 40 - 43 France Liceo RC, Mendoza
17 June, England 27 - 37 France Mendoza RC, Mendoza
17 June, Italy 20 - 23 Samoa Mendoza RC, Mendoza
17 June, Ireland 25 - 42 South Africa Liceo RC, Mendoza
21 June, Argentina 20 - 6 England Mendoza RC, Mendoza
21 June, Ireland 77 - 3 Canada Chacras RC, Mendoza
21 June, South Africa 16 - 12 New Zealand Liceo RC, Mendoza
21 June, Wales 25 - 43 Scotland Mendoza RC, Mendoza
21 June, Samoa 38 - 25 Italy Chacras RC, Mendoza
21 June, France 16 - 28 Australia Liceo RC, Mendoza
11th Place Play-Off
25 June, Italy 30 - 33 Canada Chacras RC, Mendoza
9th Place Play-Off
25 June, Ireland 34 - 17 Samoa Maristas RC, Mendoza
7th Place Play-Off
25 June, Wales 32 - 57 England Liceo RC, Mendoza
5th Place Play-Off
25 June, Argentina 39 - 7 Scotland Mendoza RC, Mendoza
3rd Place Play-Off
25 June, France 21 - 47 New Zealand Malvinas Argentinas, Mendoza
25 June, South Africa 24 - 20 Australia Malvinas Argentinas, Mendoza