1999–2000 Swiss 1. Liga

Within each group, the teams would play a double round-robin to decide their league position.

The four group winners and the four runners-up then contested a play-off for the two promotion slots.

The three last placed teams in each group were directly relegated to the newly named 2.

Due the fact that the club FC Bex had infrastructural deficiencies, they were not eligible to enter the play-offs for promotion to the Nationalliga B, this right was passed down to the third placed club in the division.

Because the teams from Naters and Meyrin ended the season level on points they had to play a league positions decider.

and runners-up Wohlen, from group 3 champions Locarno and runners up Zug 94 played together with group 4 winners Vaduz and runners-up Red Star played in the qualification round of the play-offs.

The remaining teams in the division would be joined by Stade Nyonnais and FC Schaffhausen who suffered relegation from the Nationalliga B this season.

They would also be joined by the four youth teams Servette U-21, Grasshopper Club U-21, St. Gallen U-21 and Lausanne-Sport U-21.