1999–00 National League 1

1999–2000 National League 1
Countries England
ChampionsOtley (2nd title)
Runners-upBirmingham & Solihull (also promoted)
RelegatedReading, Blackheath
Matches played182

The 1999–2000 National League 1, sponsored by Jewson, was the thirteenth full season of rugby union within the third tier of the English league system. Due to league restructuring for the 2000–01 season, the league would be renamed to National Division Two for the following season, with the old Allied Dunbar Premiership 2 being renamed as National Division One.

Otley would finish the season as league champions, and along with runners up Birmingham & Solihull would be promoted to the new look National Division One (formerly Premiership Two). Relegated sides included Reading and Blackheath who both dropped to National League 3 South.