The Heineken Cup is open to clubs in the Magners League, Guinness Premiership, Super 10 and the Top 14. Clubs that do not qualify for the Heineken Cup can enter the European Challenge Cup.
22 places are awarded by country, with each country deciding how to allocate their alloted places:
* England: 6 teams (selected by performance in Guinness Premiership and EDF Energy Cup)
* France: 6 teams (selected by performance in Top 14 Championship)
* Ireland: 3 teams (selected by performance in Magners League)
* Wales: 3 teams (selected by performance in Magners League)
* Scotland: 2 teams (selected by participation in Magners League)
* Italy: 2 teams (selected by performance in Super 10 Championship)
The remaining two places in the 24-team tournament are allocated as follows:
* One team comes from France, England or Italy; this place is allocated to the country whose team progressed further in the previous season’s Heineken Cup. For example, Toulouse have progressed further in the 2007-08 competition than any English or Italian team, so there are seven French teams in the 2008-09 competition.
* The final team is the winner of a play-off between the best placed team in the Magners League who has not already qualified, and the best placed semi-finalist in the Italian Super 10. The play-off is a single match, which takes place alternately in Italy or the home of the Magners League side. In 2007-08, this play-off was scheduled to take place before the Italian Super 10 semi-finals, so no Italian team was nominated to take part. This meant that the Magners League nominee, the Newport Gwent Dragons, qualified without a playoff.
Regardless of how well they perform domestically, the winners of the Heineken Cup and the European Challenge Cup both qualify for the next year’s Heineken Cup, and are awarded places from their countries’ allocations.
The Heineken Cup is, generally speaking, the equivalent competition of the UEFA Champions League in professional football, whereas the European Challenge Cup is the equivalent to the secondary UEFA Cup.
A proposal has been made that, in future, rather than Ireland, Wales and Scotland each sending their top-placed teams in the Magners League to the Heineken Cup, the top teams from the league as a whole should be sent, regardless of nationality.