The pool stage began with two matches on 12 October 2012 and ended on 20 January 2013.

[1] The quarter-finalists then participated in a knockout tournament that ultimately ended with the final on Saturday 18 May 2013 at Aviva Stadium in Dublin.

[3] The brackets show each team's European Rugby Club Ranking at the end of the 2011–12 season.

The draw for the pool stage took place on 12 June 2012 at Aviva Stadium.

Under rules of the competition organiser, European Rugby Cup, tiebreakers within each pool are as follows.