Ollastra is a comune (municipality) in the Province of Oristano in the Italian region Sardinia, located about 90 km northwest of Cagliari and about 14 km northeast of Oristano. Ollastra Simaxis borders the following municipalities: Fordongianus, Siapiccia, Simaxis, Villanova Truschedu, Zerfaliu. From 1928 to 1946 the place was a frazione of nearby Simaxis and was therefore known as Ollastra Simaxis. It changed its name to simply Ollastra in 1991.