This was the second season to follow the play-off structure to determine the Magners League champion, with the top four teams qualifying for the semi-finals.

[7] The following season would see RaboDirect, the Irish subsidiary of Dutch financial company Rabobank, take over the sponsorship.

The twelve teams competing were the four Irish provinces, Munster, Leinster, Connacht and Ulster; two Scottish regions, Edinburgh Rugby and Glasgow Warriors; four Welsh regions, Cardiff Blues, Newport Gwent Dragons, Ospreys and Scarlets; and two new Italian entries Aironi and Benetton Treviso In May 2010, the Ospreys were fined £100,000 and docked 4 points from the 2010–11 season following their postponement of the away fixture at Ulster in the 2009–10 season.

[8] However, in September 2010, following an appeal by the Ospreys, the four point deduction for the 2010–11 season was overturned, although the £100,000 fine was upheld.

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 caps.