The first season would see fifteen teams compete: the four Irish provinces: Connacht, Leinster, Munster and Ulster; two Scottish teams: Edinburgh Reivers and Glasgow; and all nine Welsh Premier Division teams: Bridgend, Caerphilly, Cardiff, Ebbw Vale, Llanelli, Neath, Newport, Pontypridd and Swansea.

The top four teams from each group proceeded into the knock-out phase until a champion was found.

The 2001–02 competition was dominated by the Irish teams with all four sides reaching the last eight, three progressing to the semi-finals, and the final played at Lansdowne Road contested between Leinster and Munster with Leinster running out 24–20 winners.

Wales and Scotland had joined forces for the 1999 and 2000 seasons, with the expansion of the Welsh Premier Division to include Edinburgh and Glasgow to form the Welsh-Scottish League.

Note: Flags to the left of player names indicate national team as has been defined under IRB eligibility rules, or primary nationality for players who have not yet earned international senior caps.