The Zschopau (German pronunciation: [ˈt͡ʃoːpaʊ̯], Czech: Sapava [ˈsapava] or Šopava [ˈʃopava]) is a 130-kilometre-long river in Saxony, Germany, and a left tributary of the Freiberger Mulde.

Between Scharfenstein and Zschopau, its largest left-hand tributary, the Wilisch, flows into the river by the scattered settlement of Wilischthal.

The tortuous, increasingly narrow and rocky Zschopau valley is followed by the structurally interesting Annaberg and Buchholz railway to Flöha.

In Flöha, north of the Augustusburg hunting lodge that dominates the valley landscape, it is joined by the largest tributary, named after the town.

It continues to flow through the town of Waldheim, where it is followed by the Chemnitz and Riesa railway, which runs over six viaducts on the six-kilometre-long 'bankruptcy mile' section to Limmritz.