The All-Ireland League (AIL), known for sponsorship reasons as the Ulster Bank All-Ireland League, is the national league system for the 52 senior rugby union clubs in Ireland, covering both the Republic of Ireland and Northern Ireland. The participants in the league also participate in the associated All-Ireland League Cup. The league was inaugurated in the 1990–91 season.
The league is the second highest level of rugby union in Ireland, as professional teams representing the four provinces of Ireland play in the Pro12.
Division 1 sides are allowed to field only two professional players in their matchday sides, and only one may be a forward. Professional players may not participate in Division 2 matches. Foreign professional players may not play in the League.
The All-Ireland League has been dominated by teams from Limerick who have won 13 out of 23 titles. Teams from Munster have won 17 out of 23. The All-Ireland League was not sponsored in the initial season, but was sponsored for six years by Insurance Corporation of Ireland. The League was sponsored by Allied Irish Banks from 1998 to 2010.Ulster Bank has sponsored the league since 2010.
The league is currently divided into three divisions (with Division One further divided into two sections, 1A and 1B, effectively creating a four division structure). Division One is played in the traditional double round-robin format with Divisions 2A and 2B played in a single round-robin format. The top three teams in Division 1A and the top team in Division 1B contest the end of season play-offs the determine the League champion. Play-offs also take place in Divisions 2A and 2B between the top four teams in those divisions.
From 2011 onwards, the regular season champions will be divisional champions and will in the case of the Division 1A champions, become League champions, and in the case of the other divisions, be automatically be promoted. The new structure will remain in place until at least 2017.
In each division the club finishing on top after the League series will receive a Union plaque but is not deemed the champion club of that division. Champions of each division are decided on a play-off of the top four clubs. First plays Fourth & Second plays Third. The winners then meet in a final
If a match is tied at the end of 80 minutes the following criteria determine the winner:
Extra time of ten minutes each way will be played
If still tied, the club that has scored the most tries in the game will be the winner
If still tied, the club that finished in the higher position in the league during the season will be the winner