The Regnitz is a river in Bavaria, Germany. It is an affluent of the Main and 68 km 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 in the city of Bamberg.

Large portions of the Regnitz are integrated in a canal connecting the Main with the Danube.