Ameloblastoma (adamantinoma) is a benign neoplasm deriving from the enamel organ. Its etiology has not been ultimately determined. It constitutes about 1% of all head and neck tumours, and about 11% of teeth-originating tumours. Usually it occurs in the mandible near premolar and molar teeth, more rarely in its anterior part. About 20% of described cases of ameloblastoma relate to the jaw, its very rare location is gingiva or cheak tunica mucosa. The essay presents a case of ameloblastoma of a maxillary sinus in a 65-year-old man. The diagnostic and treatment algorithm in ameloblastoma is discussed.