Ten teams played each other on a home-and-away basis, with teams earning four points for a win, and a bonus point for scoring four or more tries in a match.

The ten competing teams consisted of the four Irish provinces, Munster, Leinster, Connacht and Ulster; two Scottish regions, Edinburgh Rugby and Glasgow Warriors; and four Welsh regions, Cardiff Blues, Newport Gwent Dragons, Ospreys and Scarlets.

[3] Munster were crowned champions on 30 April 2009 after the Ospreys beat the Newport Gwent Dragons 27–18 but failed to claim a bonus point.

[4] Note: Flags to the left of player names indicate national team as has been defined under IRB eligibility rules, or primary nationality for players who have not yet earned international senior caps.

Television rights for the league are split between three broadcasters, BBC Wales, S4C and Setanta Sports.