San Agustín Chayuco is a town and municipality in Oaxaca in south-western Mexico.

The municipality covers an area of 107.2 km².

It is located in the Jamiltepec District in the west of the Costa Region.

As of 2005, the municipality had a total population of 4,514.

[1] This article about a location in the Mexican state of Oaxaca is a stub.