| Monchy-Lagache | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason fam fr Monchy.svg |
| Arrondissement: | Péronne |
| Canton: | Ham |
| Insee: | 80555 |
| Postal Code: | 80200 |
| Mayor: | Jacques Pinchon[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CC Est de la Somme |
| Coordinates: | 49.8525°N 3.0453°W |
| Elevation M: | 74 |
| Elevation Min M: | 57 |
| Elevation Max M: | 95 |
| Area Km2: | 15.44 |
Monchy-Lagache (in French pronounced as /mɔ̃ʃi laɡaʃ/) is a commune in the Somme department in Hauts-de-France in northern France.
The commune is situated on the D15 road, some 10miles west of Saint-Quentin, on the northeastern border of the département.