Santa María del Rosario is a town and municipality in Oaxaca in south-western Mexico.

The municipality covers an area of km².

It is part of the Tlaxiaco District in the south of the Mixteca Region.

[1] Although the municipality is far from the least populous in Mexico (there are dozens of smaller ones in its own State of Oaxaca, and three others in the State of Sonora), its municipal seat is the smallest in all of Mexico.

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