The Rzav (Serbian Cyrillic: Рзав) is a 72 km (45 mi) river in western Serbia and eastern Bosnia and Herzegovina.

The river originally flows northward, next to the villages of Vodice and Jokina Ćuprija, reaches the central section of the Zlatibor where it is dammed and creates the artificial Ribnica Lake (surface area of 10 km2), after the nearby village of Ribnica.

The Crni Rzav was described as an "example of the river which, under the pressure from small hydros, completely lost the diversity of its wildlife and visual identity".

Troubling changes of the habitats were recorded, as a result of drastic reduction of the water quantity and overgrowth of algae which specifically affected the aquatic macroinvertebrate fauna.

It flows between the southernmost part of the Zvijezda mountain (Ponos peak) from the north and the Suha Gora mountain from the south, next to the villages of Prosjek (and ruins of the medieval city of the same name), Dobrun and Žagree, before it empties into the Drina at the town of Višegrad.