| Große Lonau | |
| Subdivision Type1: | Country |
| Subdivision Name1: | Germany |
| Subdivision Type2: | State |
| Subdivision Name2: | Lower Saxony |
| Subdivision Type3: | Location |
| Subdivision Name3: | Northeast of Lonau in Göttingen district |
| Length Km: | 9.0 |
| Source1 Location: | South of the Hanskühnenburg |
| Source1 Elevation: | 730 m |
| Mouth Location: | Sieber |
| Mouth Elevation: | 245 m |
| Basin Size Km2: | 14 |
| Tributaries Right: | Kleine Lonau |
| Tributaries Left: | Bornwinkel |
| Custom Label: | References |
Große Lonau is a river in Lower Saxony, Germany.
The Große Lonau rises at an elevation of 730 m in the vicinity of the Hanskühnenburg on the ridge of Auf dem Acker. Then it flows mostly in a south-southwest direction to Lonau, where it merges with the Kleine Lonau. The Große Lonau discharges into the Sieber in Herzberg am Harz.