The draw, which was made in Switzerland on Tuesday, pits three-time European Cup winners Leinster alongside Harlequins and London Wasps, as well as French outfit Castres Olympique, in Pool 2.
Leinster, who last won Europe's main prize in 2012, are the RaboDirect PRO12's most successful side in Europe's top tier.
Munster, two-time winners, will also be licking their lips after being drawn in Pool 1 with last year's runners-up Clermont Auvergne.
Joining those two giants will be Saracens and Sale Sharks as last year's semi-finalists Munster look to go one better this time round.
Ulster, whose one and only European Cup triumph came in 1999, face reigning champions Toulon, Leicester Tigers and fellow RaboDirect PRO12 outfit Scarlets in Pool 3.
Pool 4 is made up of 2013/2014 RaboDirect PRO12 runners-up Glasgow Warriors, Montpellier, Bath and Toulouse while Pool 5 comprises of Ospreys, Treviso, Racing Metro 92 and Northampton.
Pool 1: Munster, Saracens, Clermont Auvergne, Sale Sharks
Pool 2: Leinster, Castres Olympique, Harlequins, London Wasps
Pool 3: Ulster, Scarlets, Toulon, Leicester Tigers
Pool 4: Glasgow Warriors, Montpellier, Bath, Toulouse
Pool 5: Ospreys, Treviso, Racing Metro 92, Northampton
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