The winners of Sunday's intriguing all-Irish quarter-final clash between top seeds Munster and Ulster will play their semi-final at the 50,000-capacity Aviva Stadium on Saturday, April 28.
Munster or Ulster will face the winners of the opening quarter-final between Edinburgh and four-time champions Toulouse.
If current English champions Saracens come through Sunday's much-anticipated contest with Clermont Auvergne, they will meet the winners of the Leinster v Cardiff Blues game in the semi-final at Twickenham Stadium on Sunday, April 29.
However, if Clermont Auvergne defeat Saracens, they will take on either Leinster or the Cardiff Blues at Stade Chaban-Delmas in Bordeaux.
The Aviva Stadium hosted last season's Heineken Cup semi-final between Leinster and Toulouse, while two tournament semi-finals have been played before at Stade Chaban-Delmas - Toulouse v Munster in 2000 and Toulouse v Biarritz Olympique in 2004.
Twickenham Stadium, which will stage this season's Heineken Cup final on May 19, has hosted one semi-final to date when London Irish met Toulouse in 2008.
2011/12 HEINEKEN CUP SEMI-FINALS:
Saturday, April 28 -
MUNSTER or ULSTER v Edinburgh or Toulouse, Aviva Stadium, Dublin
Sunday, April 29 -
Saracens or Clermont Auvergne v LEINSTER or Cardiff Blues, Twickenham Stadium, London, or Stade Chaban Delmas, Bordeaux
Heineken Cup final - Twickenham Stadium, Saturday, May 19 (kick-off 5pm)