Aladzha Monastery is a medieval Orthodox Christian cave monastery complex in northeastern Bulgaria, 17 km north of central Varna and 3 km west of Golden Sands beach resort, in a protected forest area adjacent to the Golden Sands Nature Park.

The monastery caves were hewn into a 25-m high vertical karst cliff near the upper edge of the Franga plateau on several levels. The complex includes two small nearby catacombs.

Dedicated to the Holy Trinity, it was an active hesychast monastic community of the Second Bulgarian Empire since the 12th century and perhaps survived until the early 18th century. Nearby, remains of a 5th-century cave monastery have been found.