San Mateo Etlatongo is a town and municipality in Oaxaca in south-western Mexico.

The municipality covers an area of 24.40 km2.

It is part of the Nochixtlán District in the southeast of the Mixteca Region.

As of 2005, the municipality had a total population of 1,085.

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