The Regnitz is a river in Bavaria, Germany. It is a left tributary of the Main and is 59 km (37 mi) in length.
The river is formed by the confluence of the rivers Rednitz and Pegnitz, which meet in the city of Fürth. From there the Regnitz runs northwards through the cities of Erlangen and Forchheim. It finally meets the Main near the city of Bamberg.
Between Fürth and Forchheim a lot of watermills were used from Middle Ages till 19th century. Some are still there or were reconstructed.