| Smith River | |
| Pushpin Map: | New Hampshire#USA |
| Pushpin Map Size: | 250 px |
| Subdivision Type1: | Country |
| Subdivision Name1: | United States |
| Subdivision Type2: | State |
| Subdivision Name2: | New Hampshire |
| Subdivision Type3: | Counties |
| Subdivision Name3: | Grafton, Merrimack |
| Subdivision Type4: | Towns |
| Subdivision Name4: | Grafton, Danbury, Alexandria, Hill, Bristol |
| Length: | 25miles |
| Source1: | Tewksbury Pond |
| Source1 Location: | Grafton |
| Source1 Coordinates: | 43.6067°N -71.9658°W |
| Source1 Elevation: | 924feet |
| Mouth: | Pemigewasset River |
| Mouth Location: | Bristol, Hill |
| Mouth Coordinates: | 43.5636°N -71.7278°W |
| Mouth Elevation: | 310feet |
The Smith River is a 25adj=midNaNadj=mid[1] river located in central New Hampshire in the United States. It is a tributary of the Pemigewasset River, part of the Merrimack River watershed.
The Smith River begins at the outlet of Tewksbury Pond in Grafton, New Hampshire. The river flows southwest and then southeast through Grafton, passing through Kilton Pond. Continuing through Danbury, the river remains generally flat until shortly before reaching the Alexandria-Hill town line, where it enters a narrow valley and produces several miles of whitewater. Passing under the New Hampshire Route 3A bridge at the Bristol-Hill town line, the Smith River drops over Profile Falls and arrives at the Pemigewasset River.
U.S. Route 4 follows the Smith River from its source to Danbury. NH-104 follows the river from Danbury to the east side of Alexandria.