| Leaf River | |
| Source1 Coordinates: | 42.1294°N -89.6997°W |
| Mouth Coordinates: | 42.0972°N -89.3222°W |
| Progression: | Leaf River → Rock → Mississippi → Gulf of Mexico |
| Mouth Elevation: | 676feet |
| Length: | 31miles |
| Custom Label: | GNIS ID |
The Leaf River is a tributary of the Rock River, about long,[1] in northwestern Illinois in the United States. Via the Rock, it is part of the Mississippi River watershed.
After rising east of the town of Shannon in northeastern Carroll County, the Leaf flows eastward across northwestern Ogle County, past the towns of Adeline and Leaf River. It joins the Rock River from the west between the towns of Byron and Oregon.