Celtic Rugby Director David Jordan said: "With five full rounds of Magners League fixtures still to be played, we have reached this landmark much earlier this year than last thanks in no small part to the Irish supporters that packed Lansdowne Road for the 48,000 league record crowd that watched Leinster play Ulster on New Year's Eve.
"However, in all three countries, on a like for like basis, Magners League attendances are up by nearly a quarter compared to last year with 'sold out' signs regularly appearing at Magners League games.
"The average gate is now over 6,200, almost 50% up on the figure for 2004/5, the first season the league was played in its present 11-team format," he explained.
"This shows just how popular our brand of rugby has become with success on the pitch being reflected off it, and I would like to thank all concerned for making it so."
Maurice Breen, Magners Marketing Director, added: "We are delighted that crowd attendances continue to rise in what is the inaugural Magners League season. The exciting brand of rugby played in the Magners League is being talked about throughout the rugby community, and that has to be one of the principle reasons for achieving this impressive milestone ahead of time."
In the 2005/06 season, the 500,000 total for crowds was achieved in round 20 after around 100 games, but this season the half million mark will be hit in round 17 this weekend after around 80 games.
To mark this exciting achievement, Magners Irish Cider will be choosing one randomly selected fan at each of the Magners League round 17 games this weekend. The chosen supporters will then receive complementary hospitality at their club's opening fixture for next season as well as a signed shirt.