Arnaudija Mosque, Ottoman mosque in Banja Luka, Bosnia and Herzegovina.

Arnaudija Mosque is a large Ottoman-style mosque in Banja Luka, built in 1595 under Hasan Defterdar, finance minister of the Eyalet of Bosnia. It was destroyed by explosives on 7 May 1993 and rebuilt, reopening in May 2024. It is a National Monument of Bosnia and Herzegovina.

The mosque was built in 1595 under the direction of Hasan Defterdar and ranks among the important Ottoman structures in the region. After its destruction in 1993, it lay in ruins for decades before complete reconstruction began in 2017.

The mosque's name is linked to Arnaud, a term used in Bosnia for Albanians, reflecting the role of Albanian craftsmen and Ottoman officials in the region. It was built in 1595 under Hasan Defterdar, finance minister of the Eyalet of Bosnia, and stood in the same neighbourhood as the Ferhadija Mosque, about 800 metres away.

The mosque is located in the city center and can be explored on foot; visitors should wear appropriate clothing and be mindful during prayer times. It is helpful to check opening hours beforehand and move through the interior space with respect.

The two mosques stood about 800 metres apart and were blown up on the same night, within 15 minutes of each other. Radoslav Brđanin, a Serb leader from Banja Luka, was convicted for his part in organising the destruction of Muslim property, including these mosques, and received a single 32-year sentence.