The San Dionisio Ocotepec Zapotec language is spoken by about 5,000 people in and around the town of San Dionisio Ocotepec, Oaxaca, Mexico. (Its ISO-639-3 language identification code is ZTU.)
San Dionisio Ocotepec Zapotec is one of many different Zapotec languages spoken in the Valley of Oaxaca. It is similar to the Zapotec spoken in San Pablo Güilá, but the two languages also have notable differences. San Dionisio Ocotepec Zapotec is also similar to the forms of Zapotec spoken in such places as San Lucas Quiaviní, Mitla, San Juan Guelavía, and Teotitlan del Valle.
All the Zapotec languages form a large family, Zapotec. The Zapotec languages, together with the Chatino languages, form the Zapotecan group.
Zapotecan is more distantly related to other language groups, such as Mixtecan, Chinantec, and Mazatec in a family called Oto-Manguean.