The Prut, or Pruth, (Ukrainian: Прут) is a 953 km (592 mi) long river in Eastern Europe.

It was known in antiquity as the Pyretus, Porata (possibly), Hierasus or Gerasius. It originates on the eastern slope of Mount Hoverla, in the Carpathian Mountains in Ukraine. The flows southeast eventually joining the Danube river near Reni, east of Galaţi.

Between 1918 and 1940 it was almost entirely in Greater Romania. While prior to that it also served as a border between Romania and the Russian Empire. After the World War II the river resumed its border purpose between Romania and the Soviet Union. Nowadays, for a length of 695 km it forms the border between Romania and Moldova. It has a hydrographic basin of 27,500 km2, of which 10,990 km2 are in Romania and 7,790 km2 in Moldova. The biggest city along its banks is Chernivtsi, Ukraine.

The Costeşti-Stînca/Stânca-Costeşti dam, operated jointly by Moldova and Romania, is built on the Pruth. There is also a Hydro-Electric Station in Snyatyn (Ukraine). Ships travel from the river's mouth to the city of Leova (southern Moldova). Near the city of Yaremche the river creates a waterfall Probiy which is eight meters high and has a slope of almost 45 degrees.

The following cities are situated along the river Prut, from source to mouth: Kolomyia, Chernivtsi, Ungheni, Leova and Cahul.

The following rivers are the major tributaries to the river Prut: Cheremosh, Jijia.