| San Mateo Piñas | |
| Settlement Type: | Municipality and town |
| Pushpin Map: | Mexico |
| Pushpin Label Position: | above |
| Pushpin Map Caption: | Location in Mexico |
| Subdivision Type: | Country |
| Subdivision Name: |  Mexico |
| Subdivision Type1: | State |
| Subdivision Name1: | Oaxaca |
| Area Total Km2: | 211.8 |
| Population As Of: | 2005 |
| Population Total: | 2647 |
| Timezone: | Central Standard Time |
| Utc Offset: | -6 |
| Timezone Dst: | Central Daylight Time |
| Utc Offset Dst: | -5 |
| Coordinates: | 16°N -116°W |
San Mateo Piñas is a town and municipality in Oaxaca in south-western Mexico. The municipality covers an area of 211.8 km². It is part of the Pochutla District in the east of the Costa Region.
As of 2005, the municipality had a total population of 2,647.[1]