The 2004–05 season of Luxembourg's National Division ran from 7 August 2004 to 29 May 2005. The league title was won by F91 Dudelange.
The 2004–05 season saw the National Division's roster of twelve clubs include:
The twelve teams completed the round-robin by playing each other twice (once home and once away) by 24 April. Then, the league divided into three. The top four teams were separated from the rest and formed the 'Title group' . The bottom eight teams were then subdivided into two groups of four, titled 'Relegation group A' and 'Relegation group B' . In the event, the top four were F91 Dudelange, FC Etzella Ettelbruck, Jeunesse Esch, and FC Victoria Rosport.
In each of the three mini-leagues, each team played each of the three other teams in the mini-league twice (once home and once away). To these results were added the 22 results of the first stage. The overall points totals (and goal difference, etc.) were used to determine each club's position in its respective mini-league.
After calculating the final results after 28 games, F91 Dudelange, the top team in the title group, was declared the league champion. The fourth-placed team in each of the relegation groups (Union Luxembourg and CA Spora Luxembourg in groups A and B respectively) was relegated to the Division of Honour.
This format is no longer used; the current season, 2006-07 uses a straightforward round-robin.
Luxembourg was assigned one spot in the first qualifying round of the UEFA Champions League, for the league champions; it was also assigned two spots in the first qualifying round of the UEFA Cup, for the runners-up and the winners of the Luxembourg Cup. As league champions, F91 Dudelange qualified for the Champions League. Etzella Ettelbruck qualified for the UEFA Cup as runners-up. CS Pétange qualified for the UEFA Cup by the Luxembourg Cup.