The Prut, or Pruth river (Ukrainian: Прут) is 953 km long, originating in the Carpathian Mountains in Ukraine and flowing southeast to join the Danube river near Reni, east of Galaţi.

Known in antiquity as Pyretus or Porata river.

Before 1940 and the occupation of Bessarabia and Northern Bukovina it was almost entirely in Romania. Nowadays, for a length of 711 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.

The biggest city along its banks is Chernivtsi (Cernăuţi), Ukraine.