| Sémézies-Cachan | |
| Commune Status: | Commune |
| Arrondissement: | Auch |
| Canton: | Astarac-Gimone |
| Insee: | 32428 |
| Postal Code: | 32450 |
| Mayor: | Paul Burgan[1] |
| Term: | 2020 - 2026 |
| Coordinates: | 43.5108°N 0.7319°W |
| Elevation M: | 230 |
| Elevation Min M: | 177 |
| Elevation Max M: | 281 |
| Area Km2: | 6.95 |
Sémézies-Cachan (in French pronounced as /semezi kaʃɑ̃/; Occitan (post 1500);: Semesias e Caishan) is a commune in the Gers department in southwestern France.