Santa María Chilapa de Diaz is a town and municipality in Oaxaca in south-western Mexico.

[1] The municipality covers an area of 234.75 km² at an altitude of 1900 meters above sea level.

Economic activity includes agriculture (corn, beans and wheat) and some cattle ranching.

In addition there is a factory making polyethylene products and a third dedicated to manufacture and marketing of raffia.

All the original titles were lost therefore the only data available was preserved by tradition, and it indicates that the town was founded at the banks of the River Chilar.