San Pietro al Natisone (, locally ; ; ) is a (municipality) in the Regional decentralization entity of Udine in the Italian region of Friuli-Venezia Giulia, located about northwest of Trieste and about northeast of Udine, and borders the following municipalities: Cividale del Friuli, San Leonardo, Savogna, Prepotto, Pulfero, and Torreano. Until 1878, its official Italian name was San Pietro degli Slavi, i.e. "Saint Peter of the Slavs" (cognate with the Friulian name still in use).
75.9% of the population were Slovenes according to the 1971 census.
San Pietro al Natisone is twinned with: