The 1999–2000 FIBA EuroLeague was the 43rd installment of the European top-tier level professional club competition for basketball clubs. It began on September 23, 1999, and ended on April 20, 2000. 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.

The EuroLeague, known as the Turkish Airlines EuroLeague for sponsorship reasons, is a European men's professional basketball club competition. The league is widely recognised as the top-tier men's league in Europe. The league consists of 18 teams, of which 16 are given long-term licences and wild cards, making the league a semi-closed league. The league was first organized by FIBA in 1958, subsequently by ULEB in 2000 and then solely the Euroleague Basketball.