The Red Main is a river in southern Germany. It is the southern, left headstream of the river Main. It rises in the hills of Franconian Switzerland, near Haag and flows generally northwest through the towns Creußen, Bayreuth, Heinersreuth and Neudrossenfeld. It merges with the White Main near Kulmbach to form the Main. The Red Main is 72 kilometres (45 mi) long and descends a total of 283 metres (928 ft).

The Main is the longest tributary of the Rhine. It rises as the White Main in the Fichtel Mountains of northeastern Bavaria and flows west through central Germany for 525 kilometres (326 mi) to meet the Rhine below Rüsselsheim, Hesse. The cities of Mainz and Wiesbaden are close to the confluence.