2005–06 Celtic League
The 2005–06 Celtic League was the fifth Celtic League season, and the third following the introduction of regional rugby in Wales. Eleven teams, from three countries participated. The final table was dominated by the Irish, with the top three spots taken by Ulster, Leinster and Munster respectively. The 2005–06 season was the first season for which the "free weekend" was awarded points for. Due to the odd number of teams participating, for every round of fixtures, one team has a so-called "free weekend". Each time this occurred, the team was awarded four points, so although at the end of the season it did not alter the positions, the table is skewed during the season according to the fixtures.
Teams
| Team | Stadium | Capacity | City, Area |
 Border Reivers | Netherdale | 6,000 | Galashiels, Scotland |
 Cardiff Blues | Cardiff Arms Park | 12,500 | Cardiff, Wales |
 Connacht | Galway Sportsgrounds | 5,500 | Galway, Republic of Ireland |
| Edinburgh Gunners | Murrayfield Stadium | 67,800 | Edinburgh, Scotland |
| Glasgow Warriors | Firhill Stadium Hughenden Stadium | 10,887 6,000 | Glasgow, Scotland |
| Leinster | Donnybrook Stadium | 6,500 | Dublin, Republic of Ireland |
| Llanelli Scarlets | Stradey Park | 10,800 | Llanelli, Wales |
| Munster | Thomond Park Musgrave Park | 13,200 8,300 | Limerick, Republic of Ireland Cork, Republic of Ireland |
| Newport Gwent Dragons | Rodney Parade | 12,000 | Newport, Wales |
| Ospreys | Liberty Stadium | 20,500 | Swansea, Wales |
| Ulster | Ravenhill | 12,800 | Belfast, Northern Ireland |
Table
Results
Round 1
Round 2
Welsh Round 1
- All-Welsh Round 5 matches played mid-week to allow Welsh teams to play in the Anglo-Welsh Cup.
Round 3
Round 4
Round 5
Round 6
Round 7
Round 8
Round 9
Welsh Round 2
- All-Welsh Round 9 matches postponed to allow Welsh teams to play in the Anglo-Welsh Cup.
Round 10
Round 11
Round 12
Round 13
Round 14
Round 15
Round 16
Round 10 rescheduled match
Round 17
Round 18
Welsh Round 3
- All-Welsh Round 6 matches played mid-week to allow Welsh teams to play in the Anglo-Welsh Cup.
Round 15 rescheduled match
- This match was postponed from the weekend of 4 March to allow Llanelli Scarlets to play in the Anglo-Welsh Cup semi-final.
Round 19
Round 20
Round 16 rescheduled match
Round 21
Round 17 rescheduled match
- This match was postponed from the weekend of 9 April to allow Llanelli Scarlets to play in the Anglo-Welsh Cup Final.
Round 22