Llanelli Scarlets have the toughest task of the four Welsh regions in next season's Heineken Cup. Wednesday's draw saw them placed in Pool Five with champions London Wasps, former winners Munster and powerful French side Clermont Auvergne.
The Ospreys were Wales' seeded side and face Gloucester, Ulster and Bourgoin.
Cardiff Blues have Stade Francais, Bristol and Harlequins, while Newport Gwent Dragons play Perpignan, London Irish and Benetton Treviso in Pool 1.
The draw was held at Cardiff's Millennium Stadium, which was confirmed as the venue to host next season's final on the weekend 24-25 May.
The top seeds from each of the six nations were kept apart, with Wasps, Stade Francais, Leinster, Benetton Treviso, Glasgow Warriors and the Ospreys heading up the six pools of four teams.
Heineken Cup pools 2007/8:
Pool 1: Benetton Treviso; London Irish; Perpignan; Newport Gwent Dragons
Pool 2: Ospreys; Gloucester; Bourgoin; Ulster
Pool 3: Stade Francais Paris; Bristol; Cardiff Blues; Harlequins
Pool 4: Glasgow Warriors; Saracens; Biarritz Olympique; Viadana
Pool 5: London Wasps; ASM Clermont Auvergne; Llanelli Scarlets; Munster
Pool 6: Leinster; Leicester Tigers; Toulouse; Edinburgh