| Saint-Mars-du-Désert | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason saint mars du desert.svg |
| Arrondissement: | Châteaubriant-Ancenis |
| Canton: | Nort-sur-Erdre |
| Insee: | 44179 |
| Postal Code: | 44850 |
| Mayor: | Barbara Nourry[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Erdre et Gesvres |
| Coordinates: | 47.3672°N -1.4044°W |
| Elevation M: | 67 |
| Elevation Min M: | 3 |
| Elevation Max M: | 77 |
| Area Km2: | 30.46 |
Saint-Mars-du-Désert (in French pronounced as /sɛ̃ maʁ dy dezɛʁ/; Breton: Sant-Marzh-an-Dezerzh) is a commune in the Loire-Atlantique department in western France.[2]