| Sayn/Saynbach | |
| Subdivision Type1: | Country |
| Subdivision Name1: | Germany |
| Subdivision Type2: | State |
| Subdivision Name2: | Rhineland-Palatinate |
| Subdivision Type3: | Reference no. |
| Subdivision Name3: | DE: 2712 |
| Source1 Location: | Near Himburg in the Upper Westerwald |
| Source1 Coordinates: | 50.5706°N 7.8706°W |
| Source1 Elevation: | 430 m |
| Mouth Location: | In Bendorf into the Rhine |
| Mouth Coordinates: | 50.4185°N 7.5575°W |
| Mouth Elevation: | 70 m |
| Custom Label: | References |
The Sayn (frequently also called the Saynbach) is a small river, just under long, in the south of the Westerwald hill region of Germany. It rises near Himburg in the Upper Westerwald and empties into the River Rhine in Bendorf (between the towns of Koblenz and Neuwied).