56 teams from 47 UEFA member associations participated in the 1998–99 UEFA Champions League. This was the 2nd season with 24 teams in the Group Stage. The runners-up in the 8 higher tier leagues - England, France, Germany, Greece, Italy, Netherlands, Portugal, Spain - are now entered in the UEFA Champions League. As current UEFA Champions League titleholder, Real Madrid automatically qualify for this season's competition. As they did not finish in the top 2 in the La Liga, Spain had 3 representatives.
The 1998-99 competition had 2 qualification rounds to reach the group stage.
The 32 lower tier domestic champions played a home and away knockout round.
The 16 winners from 1st Qualifying joined the 7 mid tier domestic champions and 8 higher tier domestic runners-up, playing a home and away knockout round. With the admission of Real Madrid required the Greece champions, Olympiacos to also play in this round.
The 16 winners from the 2nd Qualifying Round joined with the 8 higher tier domestic champions to form 6 groups of 4 teams, playing a home and away series.
The 6 group winners and the 2 best runners-up advanced to the knockout stage.
|Group A||Group B||Group C||Group D||Group E||Group F|
|2||Zagreb||Galatasaray||Real Madrid||Man United||Lens||Benfica|