Tertenia is a comune (municipality) in the Province of Nuoro in the Italian region Sardinia, located about 70 km northeast of Cagliari and about 25 km south of Tortolì. Tertenia borders the following municipalities: Cardedu, Gairo, Jerzu, Lanusei, Loceri, Osini, Ulassai. It is located in a high valley at the base of Mt. Arbu and Mt. Ferru, along the Rio Quirra river.