| Hornbeker Mühlenbach | |
| Mouth Location: | Elbe–Lübeck Canal near Hornbek |
| Mouth Coordinates: | 53.5614°N 10.6775°W |
| Progression: | Elbe–Lübeck Canal→ |
| Subdivision Type1: | Country |
| Subdivision Type2: | State |
| Subdivision Type3: | District |
| Length: | 7km (04miles) |
Hornbeker Mühlenbach is a long stream of Schleswig-Holstein, Germany. Its spring is near Niendorf an der Stecknitz and after passing a V-shaped valley it reaches its mouth near Hornbek into Elbe–Lübeck Canal. The river is crossing the Old Salt Route at the Mühlendamm.
It had special significance because it was part of the Limes Saxoniae since 810, which had been the border between the Abodriti and the Saxons.