The Championnat Nationale 1 is the second division of the Tunisian men's basketball system. The league is currently contested by 18 teams and is named the Nationale 1 since 2020. The highest-placed teams are promoted to the Championnat Pro A.
Format
The Nationale 1 is played in the following system:
Preliminary round: the eighteen teams are divided in two groups of nine and play each other home and away. Play-offs: the four highest placed teams from the preliminary round play each other home and away. Super Play-off: the four highest teams from the play-offs play in the semi-finals and finals which are best-of-three series. Play-out: the teams ranked 5th to 9th play each other home and away.