ERC Chairman Jean-Pierre Lux and Welsh rugby legend Ieuan Evans performed the semi-final draws, which were broadcast live on Sky Sports and www.ercrugby.com.
The winners of the Leinster v Leicester Tigers Heineken Cup quarter-final will have 'home country' advantage at the semi-final stage, with Biarritz Olympique or Toulouse their opponents.
The second semi-final will be staged in either Ireland or England as Northampton Saints or Ulster will have 'home country' advantage. Perpignan or first-time quarter-finalists Toulon will provide the opposition.
Meanwhile, in the Amlin Challenge Cup semi-finals, Munster will host either Harlequins or London Wasps if they came overcome Brive in the last-eight.
The other semi-final will be a French derby with Stade Francais or Montpellier entertaining the winners of the La Rochelle v Clermont Auvergne tie.
The semi-final matches in both competitions will be played over April 30 and May 1.
2010/11 HEINEKEN CUP SEMI-FINALS:
LEINSTER or Leicester Tigers v Biarritz Olympique or Toulouse
Northampton Saints or ULSTER v Perpignan or Toulon
2010/11 AMLIN CHALLENGE CUP SEMI-FINALS:
Stade Francais or Montpellier v La Rochelle or Clermont Auvergne
Brive or MUNSTER v Harlequins or Wasps
- Ties to be played over the weekend of April 30/May 1