The Ugar (Brzica until 1878) is a river of Bosnia and Herzegovina. It is a tributary of the Vrbas river.
The Ugar's length is around 44.5 kilometres. Its drainage basin is around 328 km2. Its largest right tributaries are: Pljačkovac, Ilomska, Kobilja, Zirin Potok and Kusin Potok (Ziro's and Kuso's creeks). The left tributaries are the creeks: namely Lužnica Potok, Dedića Potok, Andrijevića Potok, Bunar, Oraški Potok, and Kukavički Potok.
It starts at the slopes of Vlašić, upstream of Sažići and Melina villages. This is around 1590 meters above sea level. It is a watershed area of Vrbanja, Ilomska and Bila rivers. Its discharge is 6.98 m3/s (246 cu ft/s)