The 2005-06 Powergen Cup was the 35th annual rugby union cup competition in England. Originally contested between clubs of the English leagues, this was the first season for which the competition was open to the Welsh regions, forming the Anglo-Welsh Cup. The cup is contested between the twelve teams of the English Premiership and the four Welsh regional sides from the Magners League. The format of the cup is similar to that of the Heineken Cup, beginning with pool stages, with the top placed teams entering knockout stages. Each pool consists of a Welsh region and three English sides, with each team playing the others in the group once, and the top team of each group advancing to the semi-finals.