'"Boar"'; Ukrainian: Вепр, romanized: Vepr) is a river in central-eastern Poland, and a tributary of the Vistula.

It is the country's ninth longest river, with a total length of 349 km and a catchment area of 10,497 km2, all within Poland.

The river has its source in Lake Wieprz, in Wieprzów Tarnawacki near Tomaszow Lubelski, and flows into the Vistula near Dęblin.

The meandering river with its oxbow lakes is inhabited by numerous birds, European otters and Eurasian beavers.

During the Polish-Soviet War, units of the Polish 4th Army concentrated along the Wieprz, getting ready for the Battle of Warsaw.