The Rmanj Monastery (Serbian: Манастир Рмањ, romanized: Manastir Rmanj) is a Serbian Orthodox monastery dedicated to Saint Nicholas and located in Martin Brod in north-western Bosnia and Herzegovina, at the left bank of the Unac River near its confluence with the Una. The exact year of its construction cannot be determined, though the Rmanj Monastery is the westernmost Serbian Orthodox monastery at the end of the 16th century.