The Tri-Nations is the premier southern hemisphere competition. It is contested annually by Australia, New Zealand and South Africa. The launch of the Tri-Nations in 1996 was the culmination of a long standing desire to create an equivalent to the northern hemisphere's Five Nations Championship

Each team plays each other three times, expanded from two in 2006, with home advantage for two out of three of the games alternating on a yearly basis. Four points are awarded for a win and two for a draw with a bonus points system also used to reward teams for scoring four or more tries and losing by less than seven points.

Argentina were provisionally added to the tournament in 2009, with their involvement set to begin in 2012 should a stringent set of protocols be achieved.