There is a National League system of 50 senior rugby union clubs in Ireland.
The league was inaugurated in the 1990–91 season. It was not sponsored in the initial season, but was sponsored for six years by Insurance Corporation and for the last two years by Allied Irish Banks and is now known as the AIB League.
It has been dominated by teams from Munster.
1991 Cork Constitution
1992 Garryowen
1993 Young Munster
1994 Garryowen
1995 Shannon
1996 Shannon
1997 Shannon
1998 Shannon
1999 Cork Constitution
2000 St Mary's College
2001 Dungannon
2002 Shannon
2003 Ballymena
2004 Cork Constitution
2005 Shannon