The 1999–2000 season of Segunda División B of Spanish football started August 1999 and ended May 2000.
Teams from Asturias, Canary Islands, Castile and León, Community of Madrid and Galicia.
Teams from Aragon, Basque Country, Cantabria, Castile and León, Castilla–La Mancha, La Rioja and Navarre.
Teams from Balearic Islands, Catalonia, Region of Murcia and Valencian Community.
Teams from Andalusia, Castilla–La Mancha, Ceuta, Extremadura, Melilla and Region of Murcia.