| Longmesnil | |
| Commune Status: | Commune |
| Arrondissement: | Dieppe |
| Canton: | Gournay-en-Bray |
| Insee: | 76393 |
| Postal Code: | 76440 |
| Mayor: | Isabelle Duval[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CC 4 rivières |
| Coordinates: | 49.6144°N 1.6117°W |
| Elevation M: | 159 |
| Elevation Min M: | 146 |
| Elevation Max M: | 229 |
| Area Km2: | 3.86 |
Longmesnil (in French pronounced as /lɔ̃menil/) is a commune in the Seine-Maritime department in the Normandy region in northern France.
A tiny farming village situated in the valley of the river Epte in the Pays de Bray, some 38miles southeast of Dieppe on the D129 near its junction with the D156 road.