| Lachau | |
| Commune Status: | Commune |
| Image Coat Of Arms: | Blason ville fr Lachau (Drôme).svg |
| Arrondissement: | Nyons |
| Canton: | Nyons et Baronnies |
| Insee: | 26154 |
| Postal Code: | 26560 |
| Mayor: | Philippe Magnus[1] |
| Term: | 2020 - 2026 |
| Coordinates: | 44.2331°N 5.6386°W |
| Elevation M: | 750 |
| Elevation Min M: | 676 |
| Elevation Max M: | 1538 |
| Area Km2: | 25.78 |
Lachau (pronounced as /fr/) is a commune in the Drôme department in southeastern France.