Defending champions Leinster will have to negotiate their way past Clermont again if they are to retain the Heineken Cup.
Leinster beat the French side in the semi-finals before convincingly thumping Ulster in last season's final at Twickenham to clinch their third title in four years.
But they will also face the Scarlets and Heineken Cup new boys Exeter Chiefs in Pool Five.
Four-time champions Toulouse will take on Leicester, the Ospreys and Benetton Treviso in a tough-looking Pool Two
Harlequins will face Connacht for the second season along with Biarritz and new Italian side Zebre in Pool Three
Northampton Saints, beaten finalists in 2011, will take on Ulster, Glasgow Warriors and Castres in Pool Four
Last year's surprise semi-finalists Edinburgh will face Saracens, Munster and Racing Metro in Pool One.
Cardiff Blues, Toulon, Sale Sharks and Montpellier are grouped together in Pool Six
The draw in full
Pool One: Munster, Edinburgh, Saracens, Racing Metro
Pool Two: Toulouse, Leicester, Ospreys, Benetton Treviso
Pool Three: Biarritz, Harlequins, Connacht, Zebre
Pool Four: Northampton Saints, Ulster, Glasgow Warriors, Castres
Pool Five: Leinster, Clermont, Scarlets
Pool Six: Cardiff Blues, Toulon, Sale Sharks, Montpellier