The Rench is an eastern tributary of the Rhine in the Ortenau in Central Baden, Germany.

It rises on the southern edge of the Northern Black Forest at Kniebis near Bad Griesbach im Schwarzwald.

The source farthest from the mouth is that of the Schöngrundbächle which rises at a height of around 915 m above NN in the parish of Zuflucht.

The Rench runs in a prominent southerly arc through the Central Black Forest and crosses the hilly region of Ortenau with its orchards and vineyards before breaking out into the Rhine Plain.

The B 28 federal road, long an important route through the Black Forest, runs through the Rench valley linking the Strasbourg area with the upper Neckar region.