| Saint-Mars-la-Jaille | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Saint-Mars-la-Jaille (Loire-Atlantique).svg |
| Arrondissement: | Châteaubriant-Ancenis |
| Canton: | Ancenis-Saint-Géréon |
| Insee: | 44180 |
| Postal Code: | 44540 |
| Commune: | Vallons-de-l'Erdre |
| Coordinates: | 47.5261°N -1.1836°W |
| Elevation M: | 30 |
| Elevation Min M: | 22 |
| Elevation Max M: | 88 |
| Area Km2: | 20.06 |
| Population: | 2370 |
| Population Date: | 2019 |
| Population Footnotes: | [1] |
Saint-Mars-la-Jaille (pronounced as /fr/; br|Sant-Marzh-an-Olivenn) is a former commune in the Loire-Atlantique department in western France. On 1 January 2018, it was merged into the new commune of Vallons-de-l'Erdre.[2]