| Country: | IRL |
| Type: | R |
| Route: | 251 |
| Terminus A: | R250 at Doon Glebe, County Donegal |
| Terminus B: | N56 at Caoldroim Uachtarach |
| Previous Type: | R |
| Previous Route: | 250 |
| Next Type: | R |
| Next Route: | 252 |
The R251 road is a regional road in Ireland. It is located entirely in County Donegal and runs in a northerly then westerly direction from its junction with the R250 road west of Letterkenny to the N56 east of Gweedore. The route is very scenic: it passes Glenveagh, skirts around the base of Errigal and offers excellent views of the Derryveagh Mountains.