| Official Name: | San Isidro |
| Pushpin Map: | Argentina |
| Pushpin Label Position: | bottom |
| Pushpin Map Caption: | Location in Argentina |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Name1: | Catamarca |
| Subdivision Type2: | Department |
| Subdivision Name2: | Valle Viejo |
| Subdivision Type3: | 2nd level Municipality |
| Subdivision Name3: | San Isidro, Catamarca |
| Established Title: | Founded |
| Established Date: | 1698 |
| Population Total: | 4,569 |
| Coordinates: | -28.4333°N -108°W |
| Elevation M: | 515 |
| Postal Code Type: | CPA Base |
| Postal Code: | K 4707 |
| Area Code: | +54 3833 |
| Timezone: | ART |
| Utc Offset: | -3 |
San Isidro is a town in Catamarca Province, Argentina. It is the head town of the Valle Viejo Department. It forms part of the Gran San Fernando del Valle de Catamarca urban agglomeration.