We present a case of huge nasal polyp with metaplastic ossification, which obstructed left nasal cavity and nasopharynx, and provoked both nasal obstruction and sleep apnea. The patient had a history of previous sinus surgery at local hospital 30 years ago. Nasal polyp with metaplstic ossification was removed by endoscopic sinus surgery. This case highlights the importance of including metaplastic ossification of nasal polyp in the differential diagnosis of nasal cavity mass.