The Uvac (Serbian Cyrillic: Увац) is an international trans-boundary river, rising under Golija mountain and Pešter plateau, then flowing through southwestern Serbia and cross into eastern Bosnia and Herzegovina where, after 115 km, it finally meets the Lim river from the right, however, before it empties into the Lim, for a 10 kilometers Uvac forms the border between two countries.

Also, while meandering through Serbia, Uvac loosely makes the northern border of the Raška region, too.

The Uvac originates at the Pešter plateau from the Ozren and Ninaja mountains, as Rasanska reka (Cyrillic: Расанска река).

The stream curves around the Ninaja and Pometenik mountains, next to the villages of Tuzinje, Rasno, Dragojloviće and Gradac, where it meets Brnjička reka (Cyrillic: Брњичка река), enters the Sjenica depression and continues on the western border of the plain while receiving the right tributary Vapa (Cyrillic: Вапа) in the northern end.

The river is famous for its gorge, Kanjon Uvca, the thriving colony of reintroduced griffon vultures and the Uvac Special Nature Reserve, protected since 1971.