Bílina (Czech pronunciation: [ˈbiːlɪna]; German: Biela) rises on the slopes of Ore Mountains in the Czech Republic, north of Chomutov. The river flows between the Czech Central Mountains and the Ore Mountains to the north-east, and runs into the Elbe in Ústí nad Labem.
The catchment area of the river amounts to 1,071 km². In the upper part if flows through a man-made riverbed which was created when lignite mining in the area around Most started. At the same time, the former Komořany lake was drained.
A substantial part of the flow was extracted for use in chemical plants in Záluží u Litvínova. The highly polluted output killed all fish. The situation improved significantly in the 1990s. The flow rate is currently artificially increased by redirection of water from the catchment area of the Ohře. However, the Bílina is still one of the most polluted rivers in the Czech Republic.
For most of the river's length it flows through open, forestless landscape. The river bed is 5 to 10 meters wide, mostly regulated. The river has no major tributaries. Towns located around the river include Jirkov, Most, Bílina and Ústí nad Labem.