The 2011 IRB Nations Cup was the sixth edition of the international rugby union tournament, a competition created by the International Rugby Board.

It pits the "A" Teams of the stronger (Tier 1) rugby nations (e.g. Argentina Jaguars) against some Tier 2 and 3 nations (e.g.

[1] For the fifth consecutive year the event was held in Bucharest, Romania.

Namibia returned to defend their title, but South African Kings were the overall winners of the tournament.

The competition format was a modified round-robin whereby the three ENC teams (Romania, Georgia and Portugal) played the other three teams (Argentina Jaguars, Namibia and South African Kings).