The Olt River (Romanian and Hungarian; German: Alt; Latin: Aluta or Alutus, Turkish: Oltu, Ancient Greek: Ἄλυτος Alytos) is a river in Romania. It is the longest river flowing exclusively through Romania. Its source is in the Hășmaș Mountains of the eastern Carpathian Mountains, near Bălan, rising close to the headwaters of the Mureș River. It flows through the Romanian counties Harghita, Covasna, Brașov, Sibiu, Vâlcea and Olt. The river was known as Alutus or Aluta in Roman antiquity. Olt County and the historical province of Oltenia are named after the river.
Sfântu Gheorghe, Râmnicu Vâlcea and Slatina are the main cities on the river Olt. The Olt flows into the Danube river near Turnu Măgurele.