Banja Koviljača (Serbian Cyrillic: Бања Ковиљача, pronounced [bâɲa koʋǐʎatʃa]) is a popular tourist spot and spa town located in the city of Loznica, Serbia.

Banja Koviljača has a number of sulfuric and iron-bearing thermal mineral springs, ranging from 21 to 38 degrees Celsius in temperature.

The location of the spa was chosen for its proximity to useful natural elements: the Drina river, which can be forded; the wooded mountain Gučevo, which served as shelter from enemies; the plains, which supplied food; and the water, which was (and still is) considered to have medicinal properties.

Some documents state that in 1720, Turks from the city of Zvornik built a medical bathroom for women named the "Stinking Spa", due to the sulfuric water from the springs.

According to Kanić, Spa received its name from a very popular plant kovilja (Stipa pennata) which grows on nearby slopes and hills.

Development of Banja Koviljača began on 1 August 1898, when a law was passed opening it to the people of the Podrinje district for exploration.

Kur-salon, entertainment hall considered to be the most impressive building in the spa, was built in 1932 by order of King Aleksandar Karađorđević.

The mountain of Gučevo has many clear water springs which grow into smaller brooks overhung by high beech forests.