Osilo is a comune (municipality) in the Province of Sassari in the Italian region Sardinia, located about 170 km north of Cagliari and about 10 km east of Sassari. It is part of the Anglona traditional region. The municipality of Osilo contains the frazioni (subdivisions, mainly villages and hamlets) Santa Vittoria and San Lorenzo. Osilo borders the following municipalities: Cargeghe, Codrongianos, Muros, Nulvi, Ploaghe, Sassari, Sennori, Tergu. Economy is mostly based on agriculture and animal husbandry, especially of sheep, which include about 250 dairy companies. It is the production center of the Osilo pecorino cheese. Sights include a castle and several churches.