The Ohře (German: ) is a 316 km long river in Germany (65 km) and the Czech Republic (251 km), left tributary of the Elbe. The basin area of the river has a size of 6,255 km², of which 5,614 km² are in the Czech Republic and 641 km² in Germany.
The source of the river is situated in Bavaria at the foot of Schneeberg mountain in the Fichtelgebirge Range near the town of Weißenstadt. The Eger flows through the "Weissenstadt Lake" and the towns Roeslau, Marktleuthen and Hohenberg where it leaves Germany. After approx. 35 km, the Eger (not to be confused with the town in Hungary), as the river is called in German, crosses the border to Czech Republic to flow through parts of Bohemia which were known until 1945 as Egerland. The river passes the cities Cheb, (Eger, like the river), Karlovy Vary, Klášterec nad Ohří, Kadaň, Žatec, Louny, and Terezín before flowing into the river Elbe in Litoměřice.
Several districts in Germany and the Czech Republic have formed an Euroregion initiative named Euregio Egrensis to foster cooperation in the region of Eger/Ohře/Cheb.
There is a Czech pun that Ohře got its name from the river Teplá (meaning "warm" in Czech) - "ohřát" means "to warm up." However the real origin, which still shows in the German name, is Celtic from Agara (the "Salmon River"). The records show the name as Agara, Agira, Agra in 800s and Egire, Egra or Ogra in 1000s and Eger in 1472.
The highest volume flow rate occurs in spring. The average volume flow rate at the mouth is 37.94 m³/s. The lower part of the river flows through areas with the lowest average precipitation in the Czech Republic (less than 500 mm).
Ohře is primarily used for irrigation and hydroenergy. There are two dams: Skalka (built in 1962–1964, area 378 ha) and Nechranice (built 1961–1968, area 1338 ha). The rivers flows through the following important towns: Cheb, Sokolov, Loket nad Ohří, Karlovy Vary, Ostrov nad Ohří, Klášterec nad Ohří, Kadaň, Žatec, Louny, Libochovice, Budyně nad Ohří, Terezín and Litoměřice.