| Nash Stream | |
| 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: | County |
| Subdivision Name3: | Coos |
| Subdivision Type4: | Towns and townships |
| Subdivision Name4: | Columbia, Odell, Stratford, Stark |
| Length: | 15.3miles |
| Source1: | Whitcomb Mountain |
| Source1 Location: | Odell |
| Source1 Coordinates: | 44.7897°N -71.3814°W |
| Source1 Elevation: | 3140feet |
| Mouth: | Upper Ammonoosuc River |
| Mouth Location: | Stark |
| Mouth Coordinates: | 44.6256°N -71.4658°W |
| Mouth Elevation: | 942feet |
| Tributaries Left: | Pike Brook, East Branch, Pond Brook, Long Mountain Brook, Slide Brook |
| Tributaries Right: | Columbia Brook, Johnson Brook, Silver Brook |
Nash Stream is a 15.3adj=midNaNadj=mid[1] river in northern New Hampshire in the United States. It is a tributary of the Upper Ammonoosuc River and part of the Connecticut River watershed.
Nash Stream rises on the western slopes of Whitcomb Mountain in the township of Odell, New Hampshire, and flows west briefly into the town of Columbia before turning south-southwest to flow through Odell and the town of Stratford, joining the Upper Ammonoosuc River in the town of Stark. Near its headwaters, it passes through Nash Bog Pond, an extensive marshy area which used to be a large pond closed by a dam. The dam washed out in the 1960s. Nearly the entire stream is within the boundaries of the Nash Stream Forest, owned by the state of New Hampshire.
The Nash Stream watershed is surrounded by mountains. The most commonly hiked are North and South Percy Peaks, barren summits offering extensive views reached by a trail, and Sugarloaf, reached by a trail which formerly gave access to a fire tower.