A 2-year-old, female Thoroughbred racehorse was referred to the Equine Hospital of Korea Racing Authority. The horse was presented with fluctuant swelling at the base of the left temporal ear tooth. We performed physical examination, radiography and ultrasonography, and diagnosed as dentigerous cyst on the left temporal ear tooth-(dentigerous cyst). The horse was treated with removal of a dentigerous cyst(aural fistula). After surgical procedure for 12 days, the patient was recovered completely.