| Préfailles | |
| Native Name: | Pradvael |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Préfailles (Loire-Atlantique).svg |
| Arrondissement: | Saint-Nazaire |
| Canton: | Pornic |
| Insee: | 44136 |
| Postal Code: | 44770 |
| Mayor: | Claude Caudal[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | CA Pornic Agglo Pays de Retz |
| Coordinates: | 47.1333°N -2.2167°W |
| Elevation Min M: | 0 |
| Elevation Max M: | 36 |
| Area Km2: | 4.72 |
Préfailles (in French pronounced as /pʁefaj/; Breton: Pradvael) is a commune in the Loire-Atlantique department in western France.