The Marsbach or Morsbach rises southeast of Walldürn in the vicinity of the historic Roman thermae.

It flows in a northwesterly direction through Walldürn parallel to the B 47 to Rippberg, where it collects the Eiderbach.

The 22-kilometre-long Morre, also called the Saubach in its Bavarian lower reaches, has its source on the edge of the village of Hettingen.

It runs westwards through the borough of Buchen, bends towards the northwest and collects the Hollerbach.

West of Schneeberg it the Morre unites with the Marsbach to form the Billbach.