The 1999–2000 FIBA EuroLeague was the 43rd installment of the European top-tier level professional club competition for basketball clubs (now called simply EuroLeague).

The competition's Final Four was held at PAOK Sports Arena, Thessaloniki, with Panathinaikos defeating Maccabi Elite Tel Aviv in the EuroLeague Final, in front of 8,500 spectators.

For the 1999–2000 EuroLeague, the countries are allocated places according to their place on the FIBA country rankings, which takes into account their performance in European competitions from 1996–97 to 1998–99.

[2] The labels in the parentheses show how each team qualified for the place of its starting round:

(The individual scores and standings of the First stage were accumulated in the Second stage) If one or more clubs were level on won-lost record, tiebreakers were applied in the following order: