San Antonio Huitepec is a town and municipality in Oaxaca in southeastern Mexico and is the fastest shrinking municipality in Oaxaca in terms of population, with a population change of -31.5% going from the 2010 consensus to the 2020 consensus. The municipality covers an area of 199.04 km<sup>2</sup>. It is part of the Zaachila District in the west of the Valles Centrales Region.
As of 2005, the municipality had a total population of 4,303.