The pool draw for the 24 qualified clubs will be streamed live on ercrugby.com and will also launch the countdown to the Dublin 2013 Heineken Cup final at the Aviva Stadium on Saturday, 18th May.
Leinster are joined in Tier 1 by Toulouse, Munster Rugby and Northampton Saints, Biarritz Olympique and Cardiff Blues.
Once the Tier 1 clubs have each been allocated a different pool, no club from the same tier will be drawn in the same pool, and no pool will have more than one club from the same country with the exception of France, as there are seven French clubs in next season's competition.
Exeter Chiefs from England have qualified for the first time while a second Italian club will be nominated by the Italian Federation.
2012/13 Heineken Cup clubs and tiers
Tier 1 - Leinster Rugby, Toulouse, Biarritz Olympique, Munster Rugby, Cardiff Blues, Northampton Saints
Tier 2 - ASM Clermont Auvergne, Ulster Rugby, Leicester Tigers, Harlequins, Toulon, Edinburgh Rugby
Tier 3 - Ospreys, Scarlets, Glasgow Warriors, Saracens, Connacht Rugby, Sale Sharks
Tier 4 - Castres Olympique, Benetton Treviso, Racing Metro 92, Montpellier, Exeter Chiefs, Italian club (to be confirmed)
2012/13 Heineken Cup Pool Draw live on ercrugby.com on Tuesday, 12 June at 11.15am