The Saar (German: [zaːɐ̯] ⓘ; French: Sarre [saʁ] ⓘ) is a river in northeastern France and western Germany, and a right tributary of the Moselle.

It rises in the Vosges mountains on the border of Alsace and Lorraine and flows northwards into the Moselle near Trier.

Until the early 20th century, much more wine was grown on the banks of the Saar, reaching much further up from the mouth of the river, up to Saarbrücken.

The name Saar stems from the Celtic word sara (streaming water), and the Roman name of the river, saravus.

In its middle section, the Saar had been made navigable in 1866 and was used for the transport of coal (upstream) and of iron ore (downstream) in southbound direction.