Riola Sardo, also known as Arriora or Arriola in the Sardinian language, is a comune located in the Province of Oristano within the Italian region of Sardinia. The municipality is situated approximately 100 kilometres northwest of Cagliari and about 11 kilometres north of Oristano.
As of December 31, 2004, the area covered 48.2 square kilometres and had a recorded population of 2,132 residents.