2011–12 Heineken Cup pool stage
The 2011–12 Heineken Cup pool stage was the first stage of the 17th season of the Heineken Cup, Europe's top competition for rugby union clubs. It involved 24 teams competing for eight quarter-final berths, awarded to the winners of each of six pools plus the two top-ranked second-place teams. The nest three best runners-up were parachuted into the Amlin Challenge Cup.
The pool stage began with two matches on the evening of 11 November 2011, and ended on Sunday 22 January 2012. The quarter-finalists then participates in a knockout tournament that ultimately ended with the final on Saturday 19 May at Twickenham Stadium in London.
Seeding
The seeding system was the same as in the 2010–11 tournament. The 24 competing teams are ranked based on past Heineken Cup and European Challenge Cup performance, with each pool receiving one team from each quartile, or Tier. The requirement to have only one team per country in each pool, however, still applies.The brackets show each team's European Rugby Club Ranking at the end of the 2010–11 season.
| Tier 1 |  Leinster |  Toulouse | Munster |  Cardiff Blues | Biarritz |  Leicester Tigers |
| Tier 2 | Northampton Saints | Clermont Auvergne | Ospreys | Bath | Harlequins | London Irish |
| Tier 3 | Ulster | Saracens | Gloucester |  Glasgow Warriors | Scarlets | Edinburgh |
| Tier 4 | Connacht |  Benetton Treviso | Castres | Montpellier | Racing Métro | Aironi |
Pool stage
The draw for the pool stage took place on 7 June 2011. Competition organiser European Rugby Cup announced the fixtures, dates, and kickoff times for the first four rounds of pool play on 20 July 2011.Under ERC rules, tiebreakers within each pool are as follows.
- Competition points earned in head-to-head matches
- Total tries scored in head-to-head matches
- Point differential in head-to-head matches
- Tries scored in all pool matches
- Point differential in all pool matches
- Best disciplinary record
- Coin toss
| Winner of each pool, advance to quarterfinals. | |
| Two highest-scoring second-place teams advance to quarterfinals. | |
| Third- through fifth- highest-scoring second-place teams parachute into the knockout stage of the European Challenge Cup. |
All kickoff times are local to the match location.
Pool 1
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Pool 2
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Pool 3
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Pool 4
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Pool 5
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Pool 6
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