Defending champions Leinster will face Bath, Glasgow and Montpellier in the pool stages of the 2011/2012 Heineken Cup.
The Irish province beat Northampton 33-22 after an epic comeback to win their second title last month in Cardiff.
Northampton, who were among the second seeds, will play Munster, Scarlets and Castres in a tough-looking pool.
Four-time winners Toulouse will play Harlequins, Gloucester and competition debutants Connacht.
Leicester have been matched with the ever-dangerous Clermont Auvergne and Ulster, one of this season's quarter-finalists, with Italian side Aironi completing their group.
Premiership champions Saracens have managed to avoid any previous Heineken Cup winners, but two-time finalists Biarritz and Welsh region Ospreys will provide challenging opposition.
"On their day Biarritz are the strongest side," said Sarries forwards coach Alex Sanderson. "They've got some great players,"
"It's just whether they're going to turn up on the day, but you just don't know. You're going to have to look at the first four or five games of the season to see how things are going."
London Irish also find themselves in a competitive group pool with 2009 semi-finalists and 2010 Challenge Cup winners Cardiff Blues, who failed to reach the Heineken knock-out stages last season, Scottish outfit Edinburgh and big-spending Parisian side Racing Metro.
"We're in the group of entertainment," said Exiles director of rugby Toby Booth. "There's a lot of positivity there in the way the game is played.
"Edinburgh play expansively, Racing Metro have a Harlem Globetrotters all-star line-up and Cardiff Blues only know one way to play as well.
"From that point of view it should bode for some entertaining rugby, if nothing else."
Northampton, who won all six of their pool games en route to this year's final, will do well to repeat the feat next season.
They will renew acquaintances with Castres - who they beat home and away this season - and two-time winners Munster, who they shared a win apiece with in the 2009/10 pool stages, before losing in Limerick again in the quarter-finals the same year.
"The Heineken Cup is getting tougher and tougher each year and we've certainly got a challenging pool," said Saints director of rugby Jim Mallinder.
"We know first-hand how difficult it can be to play Munster and Castres from our games with them in the past two seasons. Meanwhile the Scarlets showed how dangerous they can be in their group games last year.
"However playing in this pool will be a good chance to see how much we have learned from our experiences over the past couple of years. We've had another season together as a group and have played in some big occasions."
Harlequins, who beat Stade Francais to win the Amlin Challenge Cup this season, will renew Heineken Cup acquaintances with Toulouse, who beat them twice in the pool stages [23-19 at The Stoop, 33-21 at home] two years ago.
"Every team in the Heineken Cup is going to be tough, but I'm pretty happy with the draw," said Quins full-back Mike Brown.
"We know Connacht pretty well, we seem to play them every year. Toulouse are a world-class team with world-class players.
"We played them a couple of years ago and did all right at home.
"We take a lot of confidence from beating Munster [in the semi-finals of this season's Challenge Cup] at Thomond Park and hopefully we can do something like that again."
POOL ONE: Munster, Northampton Saints, Scarlets, Castres Olympique
POOL TWO: Cardiff Blues, London Irish, Edinburgh, Racing Metro 92
POOL THREE: Leinster, Bath Rugby, Glasgow Warriors, Montpellier
POOL FOUR: Leicester, Clermont Auvergne, Ulster, Aironi Rugby
POOL FIVE: Biarritz Olympique, Ospreys, Saracens, Benetton Treviso
POOL SIX: Toulouse, Harlequins, Gloucester Rugby, Connacht Rugby