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 (and last) 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 (each team has a guaranteed 8 points), the table is skewed during the season according to the fixtures.

Teams

Table

Results

Round 1

Round 2

Welsh Round 1

Round 3

Round 4

Round 5

Round 6

Round 7

Round 8

Round 9

Welsh Round 2

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

Round 15 rescheduled match

Round 19

Round 20

Round 16 rescheduled match

Round 21

Round 17 rescheduled match

Round 22

Leading scorers

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. Players may hold one or more non-IRB nationalities.

Top points scorers

Top try scorers