The 2006 IRB Nations Cup was the first 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 (Argentina Jaguars and Italy A) against some of the Tier 2 and 3 nations (Romania and Russia).
The tournament took place between 13 and 24 June at Estádio Universitário in Lisbon, Portugal. Argentina Jaguars were the overall winners.
The competition format was a round-robin whereby each team played each of the other 3 teams once. The competition was played over three match days, with two matches played consecutively on each day.