The Breisgau S-Bahn, branded as Breisgau-S-Bahn 2020, is an S-Bahn network centered on Freiburg im Breisgau in Baden-Württemberg, Germany.

The network comprises six lines, three operated by DB Regio Baden-Württemberg and three by SWEG Südwestdeutsche Landesverkehrs-AG (SWEG):[1][2][3][4]