| Cayastá | |
| Native Name Lang: | es |
| Settlement Type: | Town |
| Pushpin Map: | Argentina |
| Pushpin Map Caption: | Location of Cayastá in Argentina |
| Coordinates: | -31.4167°N -80°W |
| Subdivision Type: | Country |
| Subdivision Name: |  Argentina |
| Subdivision Type1: | Province |
| Subdivision Name1: | Santa Fe |
| Subdivision Type2: | Department |
| Subdivision Name2: | Garay |
| Unit Pref: | Metric |
| Population Footnotes: | [1] |
| Population Total: | 3367 |
| Population As Of: | 2010 |
| Population Density Km2: | auto |
| Timezone1: | ART |
| Utc Offset1: | -3 |
| Postal Code Type: | CPA base |
| Postal Code: | S3001 |
| Area Code Type: | Dialing code |
| Area Code: | +54 342 |
Cayastá is a town (comuna) in the province of Santa Fe, Argentina. It has 3,367 inhabitants per the .
The ruins of the primitive City of Santa Fe de la Vera Cruz, from its foundation until its relocation due to the defences of the native towns and the cyclical floods, are located very close to it (approximately 1.5 kilometres southwards from its centre). Cayastá was a mocoví reduction in 1742.
The word "Cayastá" appears for the first time in an ancient document dating from 1607. For the engineer Augusto Fernández Díaz, the etymology of the toponym "Cayastá" derives from the phonetic transformation of "Kollastas" agglutination of "Kolla" and "Astay" that "denotes" moving, from where Cayastá would be "pueblo colla que se muda". Kolla was one of the villages of Aimaraes, with its own dialect, dominated by the Incas.