The Berounka is a river in the Czech Republic, a left tributary of the Vltava River. It flows through the Plzeň and Central Bohemian regions to Prague. It is formed by the confluence of the Mže and Radbuza rivers in Plzeň. Together with the Mže, which is its main source, the Berounka is 244.6 km (152.0 mi) long, which makes it the fifth longest river in the Czech Republic. Without the Mže, it is 139.4 km (86.6 mi) long.

The Vltava is the longest river in the Czech Republic, running southeast along the Bohemian Forest and then north across Bohemia, through Český Krumlov, České Budějovice and Prague, and finally merging with the Elbe at Mělník. It is commonly referred to as the "Czech national river".